Dissertations / Theses on the topic 'Atrial fibrillation; myocardial infarction'

Abstract The development of commercially available assays from the measurement of enzyme activity to mass concentrations of proteins, especially the assays of cardiac troponin I and T, has been the most important innovation in the field of cardiovascular laboratory diagnostics over the decade. The availability of a simple, rapid test using whole blood to facilitate processing and to reduce the turnaround time could improve the management of patients presenting with chest pain. The aim of this study was to evaluate the analytical and clinical performance of a new time-resolved fluorometry-based immunology technology using the cardiac marker and high-sensitivity C-reactive protein assays. In addition, the use of high-sensitivity C-reactive protein assay for the investigation of patients with acute atrial fibrillation and the influence of heparin for cardiac marker assays were studied. The levels of precision attained with pooled serum and plasma samples and control materials were acceptable. The assays were found to be linear within the ranges tested. The correlation coefficient between the Innotrac Aio! 1st generation cTnI and Abbott AxSYM cTnI assays was 0.960, and the slope was 0.07. The correlations between the 2nd generation Innotrac Aio!, Access AccuTnI and Abbott AxSYM assays were good, but there were biases between the methods. The correlation coefficients between the Innotrac Aio! and Abbott AxSYM CK-MB and myoglobin assays were 0.995 and 0.971, respectively, but the Innotrac Aio! CK-MB assay yielded about 9% higher values than the Abbott assay. The correlations between Innotrac Aio! usCRP and Cobas Integra CRP latex and between Innotrac Aio! usCRP and Hitachi CRP (Latex ) HS were good. Furthermore, the sample material correlation studies showed no significant differences when the Innotrac Aio! System was used. However, the mean Abbott AxSYM CK-MB values and the cTnI values for heparin plasma samples were 17% higher and about 15% lower than for serum samples, respectively. In the investigation of CRP levels in patients with acute atrial fibrillation CRP tended to be higher in the patients with acute FA, and there was a positive correlation between the concentrations of CRP and IL-6. The results demonstrate the excellent analytical performance of the Innotrac Aio! 2nd generation cTnI, myoglobin, CK-MB and usCRP assays, and all the matrices, including serum, plasma and whole blood, are suitable sample matrices to be used with these methods without further standardization.

Coronary artery disease (CAD) is the leading cause of mortality worldwide and atrial fibrillation (AF) is a prevalent arrhythmia associated with increased risk of mortality and morbidity. Despite improved outcome in both diseases, there is a need to further describe the prevalence, outcome and management of CAD in patients with concomitant AF. AF was a common finding among patients with MI, with 16% having new-onset, paroxysmal or chronic AF. Patients post-MI with concomitant AF, regardless of subtype, were at increased risk of composite cardiovascular outcome of mortality, MI or ischemic stroke, including mortality and ischemic stroke alone. No major difference in outcome was observed between AF subtypes. At discharge, an oral anticoagulant was prescribed to 27% of the patients with MI and AF undergoing percutaneous coronary intervention (PCI). Aspirin or clopidogrel plus warfarin versus dual antiplatelet therapy with aspirin plus clopidogrel were associated with similar 0-90-day and lower 91-365-day risk of cardiovascular outcome, without increased risk of major bleeding events. Triple therapy with aspirin, clopidogrel plus warfarin versus dual antiplatelet therapy was associated with non-significant lower risk of cardiovascular outcome, but with increased risk of bleeding events. Treatment with renin-angiotensin system (RAS) inhibitors post-MI was associated with lower risk of all-cause and cardiovascular mortality in patients with and without congestive heart failure and/or AF. However, RAS inhibition in patients without AF was not associated with lower risk of new-onset AF. Approximately 1 in 3 patients undergoing isolated coronary artery bypass grafting (CABG) had pre- or postoperative AF. Patients with AF, regardless of subtype, were at higher risk of all-cause mortality, cardiovascular mortality and congestive heart failure. Furthermore, postoperative AF was associated with higher risk of recurrent AF. In conclusion, AF was a common finding in the setting of MI and CABG. AF, irrespectively if in the setting of MI or CABG was associated with higher risk of ischemic events and mortality. Also, postoperative AF was associated with recurrent AF. Oral anticoagulants post-MI and PCI in patients with AF was underutilized, however, optimal antithrombotic therapy is still unknown. RAS inhibition post-MI seems beneficial, however, it was not associated with lower incidence of new-onset AF.

The cardiac nervous system consists of nested reflex feedback loops that interact to regulate regional heart function. Cardiac disease affects multiple components of the cardiac nervous system and the myocytes themselves. This study aims to determine: 1) how select components of the cardiac nervous system respond to acute cardiac stress, including myocardial ischemia (MI) and induced neural imbalance leading to cardiac electrical instability, and 2) how neuromodulation can affect neural-myocyte interactions to induce cardioprotection. Thoracic spinal cord stimulation (SCS) is recognized for its anti-anginal effects and ability to reduce apoptosis in response to acute MI, primarily via modulation of adrenergic efferent systems. The data presented here suggest that cervical SCS exerts similar cardioprotective effects in response to MI, but in contradistinction to thoracic SCS, uses both adrenergic and cholinergic efferent mechanisms to stabilize cardiomyocytes and the arrhythmogenic potential. SCS potentially can use efferent and/or anti-dromically activated cardiac afferents to mediate its cardioprotection. Thoracic SCS mitigates the MI-induced activation of both nodose and dorsal root ganglia cardiac-related afferents, doing so without antidromic activation of the primary cardiac afferents. Instead, thoracic SCS acts through altering the cardiac milieu thereby secondarily affecting the primary afferent sensory transduction. In response to cardiac stressors, reflex activation of efferent activity modifies mechanical and electrical functions of the heart. Excessive activation of neuronal input to the cardiac nervous system can induce arrhythmias. Stimulation of intrathoracic mediastinal nerves directly activates subpopulations of intrinsic cardiac neurons, thereby inducing atrial arrhythmias. Neuromodulation, either thoracic SCS or hexamethonium, suppressed mediastinal nerve stimulation (MSNS)-induced activation of intrinsic cardiac neurons and correspondingly reduced the arrhythmogenic potential. SCS exerted its stabilizing effects on neural processing and subsequent effects on atrial electrical function by selectively targeting local circuit neurons within the intrinsic cardiac nervous system. Together these data indicate that neuromodulation therapy, using SCS, can mitigate the imbalances in cardiac reflex control arising from acute cardiac stress and thereby has the potential to slow the progression of chronic heart disease.

Orientador: Domingo Marcolino Braile
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-11T14:35:59Z (GMT). No. of bitstreams: 1 Leal_JoaoCarlosFerreira_D.pdf: 5038174 bytes, checksum: ad94b28be3168b7ddcb5c89801eef75f (MD5) Previous issue date: 2008
Resumo: Objetivo: avaliar se há ou não associação na ocorrência de fibrilação atrial (FA) e os níveis séricos de troponina I cardíaca no pós-operatório imediato da revascularização do miocárdio (RM). Casuística e Método: estudo retrospectivo incluindo 95 pacientes submetidos à revascularização cirúrgica do miocárdio, entre dezembro de 1996 a março de 1998. Os pacientes foram divididos em 2 grupos: Grupo I constituído de 25 pacientes (26,31%) com fibrilação atrial (FA); Grupo II constituído de 70 pacientes (73,69%) sem FA. As variáveis avaliadas foram: tempos de circulação extracorpórea (CEC), pinçamento aórtico e isquemia, fração de ejeção e o diâmetro do átrio esquerdo. O ritmo cardíaco foi avaliado por monitorização contínua por exames eletrocardiográficos durante o período de internação. Todos os pacientes foram submetidos à dosagens dos níveis séricos de troponina-I cardíaca no pré e pós-operatório imediato da RM pelo método de quimioluminiscência, admitindo-se como normais valores abaixo de 0,1 ng/ml. Resultados: Os grupos I e II não apresentaram diferenças significantes quanto à fração de ejeção, diâmetro do átrio esquerdo, tempos de pinçamento da aorta e de isquemia. O tempo de CEC mostrou diferença significante entre os grupos. A análise pareada dos valores séricos da troponina I cardíaca dos pacientes dos grupos I e II no pré-operatório não mostrou diferença significante, com valor de P=0,9689. No pós-operatório, houve diferença significante entre os grupos, sendo que o grupo I mostrou maior aumento em relação ao II com P=0,0018. O valor de corte de troponina I cardíaca que melhor se associou com ocorrência de FA foi = 0,936 µg/ L. Conclusão: A ocorrência da FA está associada com os níveis séricos de troponina I cardíaca no pós-operatório imediato da RM quando considerado o valor de corte = 0,936 µg/L, sugerindo que a troponina I cardíaca é um marcador para FA e alertando para a necessidade de medidas diagnósticas ou terapêuticas preventivas
Abstract: Objective: To evaluate if there is any association among atrial fibrillation (AF) events and serum cardiac Troponin I levels in the immediate postoperative period of myocardium revascularization (MR). Patients and method: A retrospective study was made of 95 patients who underwent myocardial revascularization surgery between December 1996 and March 1998. The patients were divided into 2 groups: Group I comprised 25 patients (26.31%) who presented with atrial fibrillation (AF) and Group II 70 patients (73.69%) without AF. The variables evaluated were: time of extracorporeal circulation (ECC), aortic clamping and ischemia, ejection fraction and the diameter of the left atrium. The heart rhythm was evaluated by continuous monitoring by electrocardiography during hospitalization. The serum cardiac Troponin I levels were measured for all patients in the pre- and immediate postoperative periods of MR by chemoluminescence; normal values were consider to be below 0.1 ng/mL. Results: There were no significant differences between groups in respect to the ejection fraction, diameter of the left atrium and duration of aortic clamping and ischemia. The ECC time gave a significant difference between the groups. A comparison of the serum cardiac Troponin I levels of the patients in both groups in the preoperative period did not prove to be statistically significant (P-value = 0.9689). In the postoperative period however, there was a significant difference; Group I presented with a greater increase when compared to Group II (P-value = 0.0018). Levels of cardiac Troponin I =0.936 µg/L were associated with a risk of AF. Conclusion: AF events are associated with serum cardiac Troponin I levels =0.936 µg/L in the immediate postoperative period of MR. This suggests that cardiac Troponin I is a marker for AF, highlighting the necessity of diagnostic investigations and preventive therapeutic procedures
Doutorado
Cirurgia
Doutor em Cirurgia

La fibrillation atriale (FA) est une complication fréquente de la phase aiguë de l’infarctus (IDM) avec un moins bon pronostic des patients. Sa forme silencieuse pourrait être fréquente après un IDM. Cependant, toutes les études ayant porté sur la FA se sont focalisées sur les formes symptomatique, paroxystique ou persistante. De plus, la réduction de la biodisponibilité du •NO et la dysfonction endothéliale peuvent altérer le pronostic des patients en FA. Or, l’asymétrique diméthylarginine (ADMA) en inhibant de façon endogène l’action des NO synthases peut conduire à une dysfonction endothéliale, une inflammation ou encore à un stress oxydatif, qui sont impliqués dans de nombreuses pathologies cardiovasculaires. Cependant, au-cune étude n’a évalué la relation potentielle entre le taux plasmatique d’ADMA et la survenue d’une FA après un IDM.Notre objectif a été d’évaluer dans le cadre d’une étude prospective le pronos-tic hospitalier et à un an des patients présentant de la FA silencieuse en phase ai-guë d’IDM, et évaluer le lien potentiel entre les dimethylarginines et l’apparition d’une FA. Notre première étude prospective montre pour la première fois que la FA si-lencieuse est plus fréquente que la FA symptomatique et est associée à un moins bon pronostic après un IDM.Notre second travail, démontre que l’impact négatif de la FA silencieuse sur le pronostic des patients se maintient à un an après l’IDM.Notre troisième travail montre également, que l’ADMA est associée de ma-nière indépendante à la survenue d’une FA symptomatique après un IDM. Ces données suggèrent qu’un dépistage et qu’une prise en charge spécifiques de la FA après un IDM pourraient améliorer le pronostic des patients. L’ADMA pourrait ainsi être utilisée comme un marqueur de risque de passage en FA après un IDM
Atrial fibrillation (AF) is a frequent complication of acute myocardial infarction (AMI) with a poorer prognosis. Silent atrial fibrillation has been suggested to be frequent after AMI. However, most part of the studies has targeted only paroxysmal or persistent AF. Thus, Reduced Nitric Oxide availability and endothelial dysfunction has been recently recognized as a possible contributor to altered prognosis in AF. Asymmetric dimethylarginine (ADMA) can inhibit nitric oxide synthase and leads to endothelial dysfunction, inflammation and oxidative stress in multiple cardiovascular diseases. However, any study has addressed the relationship between ADMA levels and the occurrence of AF in AMI.We aimed to assess in-hospital and 1-year prognosis in patients experiencing silent AF in AMI and evaluate the potential relationship between dimethylarginines plasma levels and the occurrence AF after acute myocardial infarction.Our first prospective study shows for the first time that silent AF is more frequent than symptomatic AF after AMI and is associated with a worse prognosis.Our second work confirms the impact of silent AF on prognosis, with a prognosis that remains worse one year after the acute phase of MI. Our third work proved that ADMA is independently associated with symptomatic AF after AMI and strengthen the capacity to estimate symptomatic AF occurrence. In conclusion our studies highlight that AF is not a negligible event after AMI, in particular silent AF. That suggests that systematic screening and specific management should be investigated in order to improve outcomes of patients. ADMA appears to be a potential predictor of AF after AMI, because of its significant association

The overall aim of this thesis was to study the influence of physical activity on health. Risks and benefits of physical activity is of particular interest since there is a global trend of less physical activity among youths and adults. In order to investigate this aim we used a database from a large cross country ski race, Vasaloppet, with participants with a wide age range, and with both elite athletes and ordinary people who exercise and promote their health. The most serious risk of strenuous exercise is sudden death and it is challenging to identify preventive effects of major endemic diseases. Using epidemiological methodology we studied 200 000 Vasaloppet skiers and compared them with the general population. Based on personal identification numbers we added data from Swedish national personal and health registers, clinical registers as the cancer register, Swedeheart, or Swedish stroke register, and socioeconomic information from Statistics Sweden. In the Vasaloppet database we collected data on age, gender, finish time and number of races during the period 1989 to 2010. We evaluated risk of death during the race in two papers (I,II). During 90 years of annual races, cardiac arrest occurred in 20 skiers, of which five survived. The death rate is in average two per 100 000 skiers. We also studied the association with cancer incidence (paper III). The overall reduction of cancer was modest among skiers compared with the general population, but for cancers related to lifestyle the risks were markedly lower. We investigated the risk for recurrent myocardial infarction and found a 30% reduction among skiers (paper IV). In paper V we showed that skiers with a first stroke have a lower incidence of all-cause death. The skiers had a higher frequency of atrial fibrillation but had less severe stroke and no increased risk of recurrent stroke. Thus our data suggest that a lifestyle with a high level of physical activity may work as a protection after a cardiovascular event. Summary: The short excess mortality in endurance physical activity is by far outweighed by the long term protective effect of exercise in cardiovascular diseases and cancer.

Les maladies cardio-vasculaires sont la première cause de mortalité dans le monde. L’hypertrophie cardiaque est un processus de remodelage provoqué par une surcharge de travail du muscle cardiaque afin de mieux répondre à la demande de l’organisme. Bien que bénéfique à court terme, une hypertrophie trop accentuée conduira à long terme, à une insuffisance cardiaque. L’hypertrophie est associée à un remodelage électrique qui conduit généralement à un allongement du potentiel d’action, une des causes des arythmies ventriculaires et de la mort subite. Généralement, le mécanisme causal est la fibrillation ventriculaire, un trouble du rythme irréversible dont les mécanismes sont complexes et méconnus. Si les conséquences fonctionnelles in vitro des mutations génétiques ou du remodelage ionique sont relativement simples à étudier ou à prévoir, leur rôle dans les mécanismes des troubles du rythme in vivo sont plus difficiles à appréhender. Parmi les nombreux modèles animaux développés pour la recherche sur les troubles du rythme, la souris est de plus en plus utilisée en raison de notre capacité à muter, invalider ou sur-exprimer les gènes d'intérêt chez ces animaux. L'objectif de mon travail de thèse était de mieux comprendre le rôle des canaux ioniques en physiopathologie cardiaque, en particulier dans la survenue des troubles du rythme in vivo. Ces travaux ont permis d'améliorer notre connaissance du rôle des anomalies génétiques impliquant des canaux ioniques et du remodelage ionique dans la physiopathologie des troubles du rythme et pourrait ainsi ouvrir de nouvelles perspectives thérapeutiques dans le traitement anti-remodelage cardiaque et la prévention de la mort subite.
Cardiovascular disease is the leading cause of death in the world each year. If no action is taken to improve cardiovascular health and current trends continue, WHO estimates that 25% more healthy life years will be lost to cardiovascular disease globally by 2020. Cardiac hypertrophy is the consequence of an excessive workload of the heart muscle leading to cardiac remodeling process. As the workload increases, the ventricular walls grow thicker, lose elasticity and eventually may fail to pump with as much force as a healthy heart. Furthermore, hypertrophied myocardium is not physiologically normal and may confer a predisposition to potentially fatal arrhythmias. Generally, the causal mechanism is ventricular fibrillation, a cardiac rhythm disorder which is irreversible but the pathophysiological mechanisms are complex and poorly understood. The functional consequences of mutations or ionic remodeling are relatively simple to study in vitro, but their role in the pathophysiology of arrhythmias in vivo is more difficult to grasp. Among the different animal models developed in cardiac arrhythmias research, the mouse is increasingly used because of our ability to mutate, knock-out or over-express genes of interest. The objective of my thesis was to study the role of ion channels in physiology as well as cardiac pathophysiology, particularly in the involvement of the occurrence of cardiac arrhythmias in vivo. This thesis will improve our understanding of the role of genetic abnormalities involving ionic remodeling in the pathogenesis of the heart and may also open new therapeutic perspectives in the treatment of cardiac remodeling as well as sudden cardiac death.
Thèse en cotutelle avec Université de Nantes - Pays de La Loire - France (2005-2010)

Le remodelage ventriculaire gauche est une complication fréquente des patients ayantprésenté un syndrome coronarien aigu, pouvant conduire à terme à une situation d’insuffisancecardiaque. Il est donc important de connaître les facteurs associés à la survenue d’un remodelageventriculaire afin de dépister plus précocement les patients à plus haut risque d’insuffisance cardiaqueet ainsi optimiser leur prise en charge. Ce travail comprend deux axes. Le premier porte sur larecherche de nouveaux paramètres d’imagerie associés à la survenue du remodelage. Nous avonsdans un premier temps réalisé une revue de la littérature concernant la définition du remodelageventriculaire gauche en imagerie par résonance magnétique. Puis, nous avons conduit deux étudesayant pour but de rechercher une association entre (i) le strain atrial gauche et, (ii) le gradient depression intraventriculaire gauche diastolique, évalués en échocardiographie 24-48 heures après lesyndrome coronarien aigu et le remodelage ventriculaire gauche au cours du suivi. Le second axe portesur les biomarqueurs associés au remodelage ventriculaire post-infarctus. Nous avons réalisé une revuede la littérature au sujet des biomarqueurs qui, dosés lors de l’hospitalisation initiale, sont associés àl’existence d’un remodelage lors du suivi. Nous avons ensuite étudié la valeur prédictrice de deuxbiomarqueurs (la néprilysine et le coenzyme Q10) pour la survenue d’un remodelage ventriculairegauche
Left ventricular remodeling is a common complication in patients following acutemyocardial infarction and may lead to heart failure. Some baseline parameters are associated withremodeling at follow-up, allowing to better discriminate patients with an increased risk of heart failureto optimize therapeutics. This work has two axes, focused on imaging and biological parametersassociated with left ventricular remodeling, respectively. First, we reviewed past studies that definedremodeling using cardiac magnetic resonance imaging. Then, we studied the association betweensome echocardiographic parameters (left atrial strain and diastolic intraventricular pressure gradient)and left ventricular remodeling after ST-elevation myocardial infarction. In the other axis, wereviewed biomarkers that have been associated with left ventricular remodeling in prior studies. Then,we investigated the association between neprilysin and coenzyme Q10 levels and left ventricularremodeling in STEMI patients

Objective: A systematic review and meta-analysis was performed to evaluate the safety and efficacy of drug-eluting stents (DES) vs bare-metal stents (BMS) in atrial fibrillation (AF) patients. Methods: We systematically searched 5 engines until May 2019 for cohort studies and randomized controlled trials (RCTs). Primary outcomes were major bleeding and major adverse cardiac events (MACE) including cardiac death, myocardial infarction, target vessel revascularization (TVR) or stent thrombosis. Effects of inverse variance random meta-analyses were described with relative risks (RR) and their 95% confidence intervals (CI). We also stratified analyses by type (triple [TAT] vs dual [DAT]) and duration (short-vs long-term) of antithrombotic therapy. Results: Ten studies (3 RCTs; 7 cohorts) including 10,353 patients (DES: 59.6%) were identified. DES did not show higher risk of major bleeding than BMS (5.6% vs 6.9%, RR 1.07; 95%CI, 0.89–1.28, p = 0.47; I2 = 0%) or MACE (12% vs 13.6%; RR 0.96; 95%CI 0.81–1.13, p = 0.60; I2 = 44%). Although, DES almost decreased TVR risk (6.4% vs 8.4%, RR 0.78; 95%CI, 0.61–1.01, p = 0.06; I2 = 15%). Stratified analyses by type and duration of antithrombotic therapy showed no differences in major bleeding or MACE between both types of stents. In DES, long-term TAT showed higher major bleeding risk than long-term DAT (7.7% vs 4.7%, RR 1.48, 95%CI 1.08–2.03, p = 0.01; I2 = 12%). For both types of stents, MACE risk was similar between TAT and DAT. Conclusions: In patients with AF undergoing PCI, DES had similar rate of major bleeding and MACE than BMS. DAT seems to be a safer antithrombotic therapy compared with TAT.
Janssen Pharmaceuticals
Revisión por pares

Background: Acute coronary syndrome is known for its effect on cardiac function and can lead to impaired segmental and even global myocardial function. Evidence exists that myocardial revascularisation whether pharmacological, interventional or surgical results in improvement of systolic and diastolic left ventricular (LV) function, particularly that of the long axis which represents the sub-endocardial function, known as the most sensitive layer to ischaemia. Objective: We sought to gain more insight into the early effect of pharmacological and interventional myocardial revascularisation on various aspects of cardiac function including endocrine, electrical, segmental, twist, right ventricular (RV) and left atrial (LA) function. In particular, we aimed to assess the response of ventricular electromechanical function to thrombolysis and its relationship with peptides levels. We also investigated the behaviour of RV function in the setting of LV inferior myocardial infarction (IMI) during the acute insult and early recovery. In addition, we aimed to assess in detail LA electrical and mechanical function in such patients. Finally, we studied the early effect of surgical revascularisation on the LV mechanics using the recent novel of speckle tracking echocardiography technology to assess rotation, twist and torsion and the strain deformation parameters as a tool of identifying global ventricular function. Methods: We used conventionally Doppler echocardiographic transthoracic techniques including M-mode, 2-Dimentional, myocardial tissue Doppler, and speckle tracking techniques. Commercially available SPSS as a software was used for statistical analysis. Results: 1-The elevated peptide levels at 7 days post-myocardial infarction correlated with the reduced mechanical activity of the adjacent non-infarcted segment thus making natriuretic peptides related to failure of compensatory hyperdynamic activity of the non-infarcted area rather than the injured myocardial segments. 2-RV segmental and global functions were impaired in acute IMI, and recovered in 87% of patients following thrombolysis. In the absence of clear evidence for RV infarction the disturbances in the remaining 13% may represent stunned myocardium with its known delayed recovery. 3-LA electromechanical function was impaired in acute inferior STEMI and improved after thrombolysis. The partial functional recovery suggests either reversible ischaemic pathology or a response to a non-compliant LV segment. The residual LA electromechanical and pump dysfunction suggest intrinsic pathology, likely to be ischaemic in origin. 4-LV function was maintained in a group of patients with multivessel coronary artery disease who underwent coronary artery bypass graft (CABG) surgery. Surgical myocardial revascularisation did not result in any early detectable change in the three functional components of the myocardium, including twist and torsion, as opposite to conventional percutaneous coronary intervention (PCI). Conclusion: The studied different materials in this thesis provide significant knowledge on various aspects of acute ischaemic cardiac pathology and early effect of revascularisation. The use of non-invasive imaging, particularly echocardiography with its different modalities, in studying such patients should offer immediate thorough bed-side assessment and assist in offering optimum management.

[EN] The behavior of the heart is governed by electrical currents generated in the myocardium, and therefore, the study of the cardiac electrical activity is essential for the diagnosis of cardiac diseases. The forward problem of the electrocardiography (FP) entails the calculation of the torso potentials from the electrical activity of the heart and the 3D body model, while the inverse problem (IP) resolution allows the noninvasive reconstruction of the electrical activity of the heart from surface potentials. The IP is of great importance in clinical applications since it allows estimating the electrical activity of the myocardium with only noninvasive recordings. However, IP resolution is still a big challenge in electrocardiography since it is ill-posed, very unstable and has multiple solutions. In this thesis different algorithms and strategies based on the IP resolution were developed and applied in the noninvasive diagnosis of ventricular and atrial arrhythmias and evaluated with mathematical cellular models and clinical data bases. The thesis focuses on the IP resolution for the noninvasive reconstruction of the myocardial electrical activity for different diseases and propagation patterns, implementing a novel system for complex propagation patterns. The obtained results and propagation patterns were evaluated and classified with the corresponding optimal resolution strategy that minimizes the error and increases the stability of the system, proving its advantages and disadvantages depending on the different diseases and their activation pattern. A novel iterative method was implemented for the IP dipolar resolution optimized for representing simple propagation patterns, achieving a high stability and robustness against noise by constraining the solution to a limited number of dipoles. However, propagation patterns not representable by few dipoles need to be computed with the IP in terms of epicardial solutions which provide a more detailed estimation of the myocardial activity. IP resolution in the voltage and phase domains showed a good accuracy for simple and organized propagation patterns. This method allowed the noninvasive diagnosis of the Brugada syndrome or the location of ectopic focus in atrial arrhythmias by performing a parametric analysis of the electrograms morphology or the activation map reconstruction. However, mathematical and patient results presented in this thesis proved that, for complex propagation patterns like atrial fibrillation (AF), inverse solutions in the voltage and phase domains are over-smoothed and over-optimistic, simplifying the complex AF activity, leading to non-physiological results that do not match with the complex intracardiac electrograms recorded in AF patients. In this thesis, we proposed a novel technique for the noninvasive identification and location of high dominant frequency AF sources, based on the assumption that in many cases atrial drivers present the highest activation rate with an intermittent propagation to the rest of the tissue that activates at a slower rate. Although, voltage and phase inverse solutions for AF complex propagation patterns were over smoothed and inaccurate, the noninvasive estimation of frequency maps was significantly more accurate, allowing the identification of the AF frequency gradient and location of high frequency sources. This technique may help in planning ablation procedures, avoiding unnecessary interseptal punctures for right-to-left frequency gradients cases and facilitating the targeting of the AF drivers, reducing risk and time of the clinical procedure.
[ES] El comportamiento del corazón se rige por corrientes eléctricas generadas en el miocardio y, por lo tanto, el estudio de su actividad eléctrica es esencial para el diagnóstico de enfermedades cardíacas. El problema directo (PD) de la electrocardiografía implica el cálculo de los potenciales del torso a partir de la actividad eléctrica del corazón y el modelo 3D del cuerpo, mientras que la resolución del problema inverso (PI) permite la reconstrucción no invasiva de la actividad eléctrica del corazón a partir de los potenciales de superficie, cobrando una gran importancia en la práctica clínica. Sin embargo, sigue siendo un gran desafío para la electrocardiografía ya que está mal planteado, es muy inestable y tiene múltiples soluciones. A lo largo de esta tesis se han desarrollado diferentes estrategias para la resolución del PI, aplicándolas en el diagnóstico no invasivo de arritmias ventriculares y auriculares, verificándolas mediante modelos celulares matemáticos y bases de datos clínicas. La tesis se centra en la resolución del PI para la reconstrucción no invasiva de la actividad eléctrica del miocardio para diferentes enfermedades cardiacas con diferentes patrones de propagación, implementando un novedoso sistema para patrones de propagación complejos. Además, se han validado los resultados obtenidos y se han clasificado los diferentes patrones de propagación con la estrategia de resolución del PI óptima que minimice el error y aumente la estabilidad del sistema. Un nuevo método iterativo fue implementado para la resolución del PI para fuentes dipolares, siendo óptimo para representar patrones de propagación simples, logrando una alta estabilidad e inmunidad al ruido al restringir la solución a un número limitado de dipolos. Sin embargo, los patrones de propagación que no pueden ser representados por un número limitado de dipolos deben calcularse mediante la resolución del PI en términos de potenciales epicárdicos, proporcionando una estimación más detallada de la actividad del miocardio. La resolución del PI en el dominio de la tensión y fase mostró ser muy preciso para patrones de propagación simples y organizados. Este método permite el diagnóstico no invasivo del síndrome de Brugada o la ubicación de focos ectópicos en arritmias auriculares mediante un análisis paramétrico de la morfología de los electrogramas o la reconstrucción de los mapas de activación. Sin embargo, los resultados matemáticos y clínicos presentados en esta tesis demostraron que, para patrones de propagación complejos como la fibrilación auricular (FA), los resultados obtenidos mediante la resolución del PI en el dominio de la tensión y fase son demasiado suaves y optimistas, simplificando enormemente la complejidad de la FA, llevando a resultados no fisiológicos que no coinciden con la actividad compleja de los electrogramas intracardiacos registrados en pacientes con FA. En esta tesis, se ha propuesto una novedosa técnica para la identificación y localización no invasiva de fuentes con una frecuencia dominante alta, basado en la suposición de que en muchos casos las fuentes eléctricas que generan y mantienen la FA presentan una tasa de activación más alta, con una propagación intermitente hacia el resto del tejido auricular cuya frecuencia de activación es más lenta. Aunque las soluciones en el dominio de la tensión y fase para patrones de propagación complejos fueron más suaves y menos precisas, la estimación no invasiva de los mapas de frecuencia fue significativamente más precisa, permitiendo la identificación del gradiente de frecuencia y ubicación de las fuentes de FA de alta frecuencia. Esta técnica puede ser de gran ayuda en la planificación de los procedimientos de ablación, evitando punciones interseptales innecesarias para casos con un gradiente de frecuencia de derecha a izquierda y facilitando la localización de las fuentes de alta frecuencia
[CAT] El comportament del cor es regeix per corrents elèctrics generades en el miocardi i, per tant, l'estudi de la seua activitat elèctrica és essencial per al diagnòstic de malalties cardíaques. El problema directe (PD) de l'electrocardiografia implica el càlcul dels potencials del tors a partir de l'activitat elèctrica del cor i el model 3D del cos, mentre que la resolució del problema invers (PI) permet la reconstrucció no invasiva de l'activitat elèctrica del cor a partir de els potencials de superfície. La resolució del PI de l'electrocardiografia té una gran importància en la pràctica clínica atès que fa possible una estimació de l'activitat elèctrica del miocardi únicament a partir de registres no invasius. No obstant això, la resolució del PI segueix sent un gran desafiament per a la electrocardiografia ja que està mal plantejat, és molt inestable i té múltiples solucions. Al llarg d'aquesta tesi s'han desenvolupat diferents estratègies basades en la resolució PI, aplicant-les en el diagnòstic no invasiu d'arítmies ventriculars i auriculars, verificant mitjançant models cel·lulars matemàtics i bases de dades clíniques. La tesi se centra en la resolució del PI per a la reconstrucció no invasiva de l'activitat elèctrica del miocardi per a diferents malalties cardíaques amb diferents patrons de propagació, implementant un nou sistema per a patrons de propagació complexos. A més se han validat els resultats obtinguts i se han classificat els diferents patrons de propagació amb l'estratègia de resolució del PI òptima que minimitze l'error i augmente l'estabilitat del sistema. Un nou mètode iteratiu va ser implementat per a la resolució del PI per fonts dipolars, sent òptim per representar patrons de propagació simples, aconseguint una alta estabilitat i immunitat al soroll en restringir la solució a un nombre limitat de dipols. No obstant això, els patrons de propagació que no poden ser representats per un nombre limitat de dipols s'han de calcular mitjançant la resolució del PI en termes de potencials epicàrdics, proporcionant una estimació més detallada de l'activitat del miocardi. La resolució del PI en el domini de la tensió i fase va mostrar ser molt precís per a patrons de propagació simples i organitzats. Aquest mètode permet el diagnòstic no invasiu de la síndrome de Brugada o la ubicació de focus ectòpics en arítmies auriculars mitjançant una anàlisi paramètric de la morfologia dels electrogrames o la reconstrucció dels mapes d'activació. No obstant això, els resultats matemàtics i clínics presentats en aquesta tesi van demostrar que, per patrons de propagació complexos com la fibril·lació auricular (FA), els resultats obtinguts mitjançant la resolució del PI en el domini de la tensió i fase són massa suaus i optimistes, simplificant enormement la complexitat de la FA, obtenint resultats no fisiològics que no coincideixen amb l'activitat complexa dels electrogrames intracardiacos registrats en pacients amb FA. En aquesta tesi, s'ha proposat una nova tècnica per a la identificació i localització no invasiva de fonts amb una freqüència dominant alta, basat en la suposició que en molts casos les fonts elèctriques que generen i mantenen la FA presenten una taxa d'activació més alta, amb una propagació intermitent cap a la resta del teixit auricular on la freqüència d'activació és més lenta. Encara que, les solucions en el domini de la tensió i fase per patrons de propagació complexos van ser més suaus i menys precises, l'estimació no invasiva dels mapes de freqüència va ser significativament més precisa, permetent la identificació del gradient de freqüència i ubicació de les fonts de FA d'alta freqüència. Aquesta tècnica pot ser de gran ajuda en la planificació dels procediments d'ablació, evitant puncions interseptales innecessaris per a casos amb un gradient de freqüència de dreta a esquerra i facilitant la
Pedrón Torrecilla, J. (2015). Non-invasive Reconstruction of the Myocardial Electrical Activity from Body Surface Potential Recordings [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58268
TESIS

Avaliamos os efeitos da estimulação atrial temporária na prevenção da fibrilação atrial no pós-operatório de revascularização do miocárdio com circulação extracorpórea e identificamos os fatores de risco para o aparecimento dessa arritmia. Estudamos 240 pacientes que ao término da cirurgia de revascularização miocárdica submeteram-se ao implante de eletrodos epicárdicos na parede lateral do átrio direito e no teto do átrio esquerdo e foram randomizados em grupo não estimulado, grupo com estímulo atrial direito e grupo com estímulo simultâneo nos átrios direito e esquerdo. Concluímos que a estimulação atrial temporária reduziu a incidência de fibrilação atrial pós-operatória e que a idade avançada e a não estimulação atrial foram fatores preditivos independentes para a ocorrência da arritmia
We studied the effects of temporary atrial pacing to prevent the atrial fibrillation after coronary artery bypass graft surgery and the risk factors to occurrence of this arrhytmia. We followed-up 240 patients after coronary artery bypass graft surgery who suffered temporary pacing atrial implantation at the end of operation. The patients were randomized into three groups according pacing stimulation into right atrial pacing, biatrial pacing and no stimulated patients. We concluded that the temporary atrial pacing reduced the incidence of postoperative atrial fibrillation. In addition older age was also a predictive factor of occurrence of atrial fibrillation

La majorité des morts subites correspond à un infarctus du myocarde, c'est-à-dire à une occlusion aiguë d'une artère coronaire, compliqué de trouble du rythme ventriculaire. On ne sait pas pourquoi à degré d'ischémie myocardique équivalent, à âge, sexe et statut clinique égaux, un patient développera des arythmies ventriculaires alors qu'un autre n'aura aucune complication rythmique. Dans cette étude, nous aborderons deux approches de l'étude de la mort subite. D'une part, le recueil de données biologiques et cliniques et d'autre part une approche génétique. Ainsi, il a été mis en évidence que le polymorphisme Gln27Glu du gène ADRB2 semble prédisposer les patients à l'apparition rapide de la fibrillation ventriculaire dans le cadre d'une ischémie cardiaque. Cette étude suggère également que la présence de variants dans le gène GJA1 près de résidus soumis à la méthylation pourrait être liée à la survenue de la fibrillation ventriculaire chez les patients avec infarctus du myocarde. Ces nouvelles données permettent d'améliorer les connaissances sur la mort subite à la phase aiguë de l'infarctus du myocarde et d'envisager dans le futur de nouvelles stratégies de prévention
The majority of cardiac sudden deaths correspond to a myocardial infarction, ie an acute occlusion of a coronary artery, complicated by ventricular arrhythmia. It is not known why, at equivalent degree of myocardial ischemia, at equal age, sex and clinical status, one patient will develop ventricular arrhythmias while another will have no rhythmic complication.In this study, we will discuss two approaches to the study of sudden death. On the one hand, the collection of biological and clinical data and on the other hand a genetic approach.Thus, it has been shown that the Gln27Glu polymorphism in the ADRB2 gene seems to predispose patients to the rapid onset of ventricular fibrillation in the setting of cardiac ischemia. This study also suggests that the presence of variants in the GJA1 gene near residues subjected to methylation may be related to the occurrence of ventricular fibrillation in patients with myocardial infarction.These new data help to improve knowledge on sudden death in the acute phase of myocardial infarction and to consider new prevention strategies in the future

Postoperative atrial fibrillation (AF) after cardiac surgery with cardiopulmonary bypass (CPB) remains unresolved problem. Some authors noticed that there were changes in electrolyte balance after coronary artery bypass grafting (CABG) surgery with CPB. The changes in serum magnesium level and their relation with the rate of postoperative AF are usually analyzed in scientific publications. The aim of the study has been to estimate the relationship between the rate of postoperative AF and the changes in serum electrolyte concentration and their urinary excretion after CABG surgery with CPB. The goals: 1) To estimate the rate and the character of postoperative AF and its influence on haemodynamics after CABG surgery. 2) To estimate changes in serum K+, Na+, Mg++, Ca++, Cl–, P– concentration and compare them between the patients who received, and who did not receive magnesium sulphate supplementation during the surgery. 3)To estimate changes of urinary excretion of K+, Na+, Mg++, Ca++, Cl–, P– and compare them between the patients who received, and who did not receive magnesium sulphate supplementation during the surgery. 3) To evaluate the effects of intraoperatively infused magnesium sulphate on the rate of postoperative AF in the early postoperative period. In our study the rate of postoperative AF was 27.4 %. AF in 91.3 % of cases was tachyarrhythmic, but haemodynamic remained stabile. Serum Mg++ level was > 1.05 mmol/l during the suregry in all patients. The infusion of... [to full text]

Introduction: Ventricular arrhythmias (VAs) are common after an acute coronary syndrome (ACS) and are associated with worse clinical outcomes. However, little is known about recent trends in their occurrence, their association with serum glucose levels, and their psychological impact in ACS setting. Methods: We examined 25-year (1986-2011) trends in the incidence rates (IRs) and hospital case-fatality rates (CFRs) of VAs, and the association between serum glucose levels and VAs in patients with an acute myocardial infarction (AMI) in the Worcester Heart Attack Study. Lastly, we examined the relationship between in-hospital occurrence of VAs and 12-month progression of depression and anxiety among hospital survivors of an ACS in the longitudinal TRACE-CORE study. Results: We found the IRs declined for several major VAs between 1986 and 2011while the hospital CFRs declined in both patients with and without VAs over this period. Elevated serum glucose levels at hospital admission were associated with a higher risk of developing in-hospital VAs. Occurrence of VAs, however, was not associated with worsening progression of symptoms of depression and/or anxiety over a 12-month follow-up period in patients discharged after an ACS. Conclusions: The burden and impact of VAs in patients with an AMI has declined over time. Elevated serum glucose levels at hospital admission may serve as a predictor for in-hospital occurrence of serious cardiac arrhythmias. In-hospital occurrence of VAs may not be associated with worsening progression of symptoms of depression and anxiety in patients with an ACS.

Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in the clinical practice. However, the underlying mechanism or pathophysiology is not fully understood despite our extensive research on AF. Furthermore, AF is commonly complicated by myocardial infarction (MI) with an incidence rate as high as 22%. Atrial fibrillation is also associated with poor short and long-term outcome after acute myocardial infarction. Although the association between myocardial infarction and AF is well established, our knowledge of the underlying mechanism by which MI leads to AF remains incomplete. This thesis focused on the pathophysiology of AF during MI in the clinical and bench-side setting. It also examined the prognostic value of AF post MI. Chapter 2 is a systematic review and meta-analysis showing us the trend in AF incidence and prognosis over the last three decades with our advancement in both intervention and pharmacological therapy. The study reveals a significant declining in AF incidence post MI; however, mortality remains higher compared to non-AF even during the interventional era (2000s). This may be attributed to the fact that AF patients are older with more comorbidities and had less invasive procedures compared to non-AF patients but clearly more work is required in this area. Chapter 3 focused on the mechanism of AF during the acute phase (60 minutes) of myocardial infarction. This was ovine model of myocardial infarction which was induced by percutaneous approach via the right femoral artery using angioplasty technique to induce infarct. The study involved 36 sheep divided into 3 groups; the first group included 12 animals with proximal left circumflex occlusion (LCX) to induce myocardial infarction with left atrial infarction or ischaemia. The second group included 12 animals with proximal occlusion of the left anterior descending artery (LAD) to induce myocardial infarction without left atrial ischaemia or infarction, and the third group included 12 sham animals which underwent the same procedure without induction of myocardial infarction. This model was unique as both LAD and LCX supply almost equivalent myocardium but the LCX only supplies the left atrium. The study found that occlusion of the LCX (MI with LA ischaemia) resulted in significant conduction slowing, greater inhomogeneity in conduction and more AF inducibility and duration compared to LAD group or controls. On the other hand, occlusion of LAD resulted in only moderate conduction slowing with a slight inhomogeneity in conduction compared to controls. The study concludes that atrial ischaemia is the dominant substrate for AF after MI. However, there is additional contribution to this substrate due to raised intra-atrial pressure with diastolic dysfunction which is associated with left ventricular infarction. Chapter 4 examined the role of atrial branches (left atrial ischaemia) disease on AF genesis during acute myocardial infarction in humans. This is a case-control study in which cases and controls were selected from a pool of 2460 patients who presented with AMI between 2005 and 2009. A total of 42 patients with left atrial branches disease (proximal lesion in right coronary artery or left circumflex artery) were matched with 42 control patients (MI patients with lesion distal to the left atrial branches). Both groups were also matched for left ventricular ejection fraction, age and sex. The study concluded that coronary artery disease affecting the atrial branches was an independent predictor for the development of atrial fibrillation after MI. Chapter 5 focused on characterisation of left atrial remodeling of patients with coronary artery disease affecting the left atrial branches (atrial ischaemia) after AMI. In this case-control study, 26 consecutive patients with acute myocardial infarction and coronary artery lesion affecting the left atrial branches were matched with another 26 patients with MI without LA branches disease according to age, sex, body mass index and left ventricular ejection fraction. The study highlighted the importance of left atrial branches disease or atrial ischaemia results in left atrial structural remodeling characterised by atrial enlargement and this was independent of end diastolic pressure load (1), age, sex or left ventricular ejection fraction. It provides further evidence for the importance of atrial ischemia to the development of the substrate for AF. Chapter 6 looked at the association between new onset AF and post MI ventricular fibrillation and the long-term outcome. From a prospectively collected cohort of 3200 patients with MI, 96 patients with new onset AF were matched 1:3 with 288 patients with no AF on the basis of left ventricular ejection fraction. The incidence of VF arrest during admission and long-term mortality was significantly higher in AF patients independent of LVEF. In summary, AF post MI remains a poor prognostic indicator despite our advancement in intervention and pharmacotherapy. Although AF patients are usually older with multiple comorbidities, AF remains an independent predictor of poor outcome after MI. This is probably related to the total ischaemic burden (involvement of left atrium) and rapid ventricular rate in already compromised ischaemic myocardium. The mechanisms of AF during MI are a combination of atrial ischaemia or infarction, atrial stretch due to raised end diastolic pressure with diastolic dysfunction during MI. In addition, there may be neurohumoral and autonomic factors that play an additive role in the pathophysiology of AF in patients with MI. Finally, the management of AF post MI is suboptimal with lack of evidence-based medicine. Further studies require determining the optimal antiarrhythmic as well as the best anticoagulation regime, especially in those who require dual antiplatelet therapy.
Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2015

Trabalho Final do Mestrado Integrado em Medicina apresentado à Faculdade de Medicina
Introduction: The cornerstone of atrial fibrillation (AF) catheter ablation is pulmonary vein isolation (PVI), either using point-by-point radiofrequency ablation (RF) or single-shot ablation devices, such as cryoballoon ablation (CB). However, achieving permanent transmural lesions is difficult and pulmonary vein (PV) reconnection is common. Elevation of high-sensitivity Troponin I (hsTnI) may be used as a surrogate marker for transmural lesions. Still, data regarding the comparison of hsTnI increase after PVI with RF or cryo-energy is scarce. The aim of this study is to compare the magnitude of hsTnI elevation after PVI with CB versus RF using Ablation Index (AI) guidance. Methods: Prospective study of 28 patients admitted for first ablation procedure of AF in a single tertiary Cardiology Department. Fourteen patients were submitted to PVI using CB and 14 patients were submitted to RF using CARTO® mapping system and AI guidance. Patients with atrial flutter or long-standing persistent AF were excluded. Baseline characteristics were compared between groups, as well as hsTnI before and after the procedure. Results: Mean age was 59.8±12.8 years old, 50% of patients were male and 82.1% had paroxysmal AF. There were no significant differences between groups regarding demographic characteristics or comorbidities (namely prevalence of arterial hypertension, dyslipidaemia, diabetes or obesity) or regarding AF type. There was also no significant difference in electrical cardioversion need during the ablation procedure. HsTnI median value before ablation was 4.4±5.6 ng/dL in CB-group versus 2.7±1.8 ng/dL in RF-group (p=0.421). After the procedure, the variation of hsTnI was significantly higher in CB-group (2846.4 ± 2411.8 ng/dL versus 632.8 ± 401.5 ng/dL RF; p=0,005). There were no periprocedural complications. During a mean follow-up of 6.0±4.1 months there was no significant difference regarding FA recurrence (14.3% RF vs. 7.1% CB, p=0.549). Conclusions: High-sensitivity Troponin I was significantly elevated after PVI, irrespective of the ablation technique. In CB-group, hsTnI variation was significantly higher than in RF-group. This disparity may reflect more extensive or deeper transmural lesions with cryoablation. Further studies are needed to understand whether this hsTnI elevation is predictive of a lower long-term AF recurrence rate.
Introdução: A base da ablação por catéter da fibrilhação auricular (FA) assenta no isolamento das veias pulmonares (IVP), usando a ablação ponto-a-ponto por radiofrequência (RF) ou a técnica de single-shot como a crioablação (CB). No entanto, lesões transmurais permanentes são de difícil obtenção e a reconexão das veias pulmonares (VP) é comum. A elevação de troponina I de alta sensibilidade (hsTnI) pode ser usada como um marcador das lesões transmurais. No entanto, os dados sobre a comparação da elevação da hsTnI após as duas técnicas de ablação de FA são escassos. O objetivo deste estudo é comparar a magnitude da elevação de hsTnI após o IVP com CB versus RF guiada por Ablation Index (AI). Métodos: estudo prospetivo com 28 doentes admitidos para o primeiro procedimento de ablação de FA no serviço de Cardiologia dum hospital terciário. Destes doentes, 14 foram submetidos a IVP por CB e 14 por RF utilizando o sistema de mapeamento CARTO® e AI. Doentes com flutter auricular ou com FA persistente de longa duração foram excluídos. As características basais da amostra foram comparadas entre os dois grupos, assim como a hsTnI antes e após procedimento. Resultados: A idade média foi de 59,8±12,8 anos, 50% dos doentes eram do sexo masculino e 82,1% tinham FA paroxística. Não se verificaram diferenças significativas entre os dois grupos relativamente a características demográficas e comorbilidades (nomeadamente prevalência de hipertensão arterial, dislipidemia, diabetes, obesidade) ou em relação ao tipo de FA. Não houve diferença significativa entre os dois grupos quanto à necessidade de cardioversão elétrica durante o procedimento de ablação de FA. A média de hsTnI antes de ablação foi de 4,4±5,6 ng/dL no grupo de CB e de 2,7±1,8 ng/dL no grupo de RF (p=0,421). Após o procedimento, a variação de hsTnI foi significativamente maior no grupo da CB (2846,4±2411,8 ng/dL vs. 632,8±401,5 ng/dL RF; p=0,005). Durante o follow-up médio de 6,0±4,1 meses não se verificou uma diferença significativa na taxa de recorrência de FA (14,3% RF vs. 7,1% CB, p=0,549). Conclusão: A hsTnI aumentou substancialmente após o IVP independentemente da técnica de ablação. No grupo submetido a CB, a variação da hsTnI foi significativamente maior do que no grupo submetido a ablação por RF. Esta disparidade pode traduzir-se em lesões mais extensas ou profundas na CB. Estudos complementares são necessários para perceber se a elevação da hsTnI é preditiva de uma menor taxa de recorrência de FA a longo prazo.

Contexte: La maladie de Fabry (MF) se caractérise par l'accumulation de sphingolipides dans de multiples organes dont l'oreillette gauche (OG). La littérature existante ne permet pas d'établir si les fonctions réservoir, conduit et pompe de l'OG étudiées par échocardiographie de suivi des marqueurs acoustiques (speckle-tracking echocardiography, STE) sont affectées dans la MF et si la thérapie de remplacement enzymatique (TRE) permet d'améliorer la fonction de l'OG. Méthodes: Dans cette étude de cohorte rétrospective, la déformation, le taux de déformation et les volumes phasiques de l'OG ont été étudiés chez 50 patients atteints de la MF et comparés à 50 contrôles sains. Résultats: Les trois fonctions phasiques de l'OG étaient altérées. La déformation positive maximale (fonction réservoir) était de 38,9 ± 14,9 % vs. 46,5 ± 10,9 % (p=0,004) et la déformation télédiastolique (fonction pompe) était de 12,6 ± 5,9 % vs. 15,6 ± 5,3 % (p=0,010). Chez 15 patients ayant débuté la TRE pendant l'étude, la majorité des paramètres de fonction de l'OG se sont améliorés après un suivi d'un an (déformation positive maximale de 32,0 ± 13,5 % à 38,0 ± 13,5 %; p=0,006) alors qu'il y a eu une tendance vers une détérioration des paramètres chez 15 patients n'ayant jamais reçu de traitement (déformation positive maximale de 47,3 ± 10,8 % à 41,3 ± 9,3 %; p=0,058). Neuf patients atteints de la MF (21%) ont développé une fibrillation auriculaire ou un accident vasculaire cérébral pendant un suivi de quatre ans. La déformation positive maximale et la déformation protodiastolique étaient plus fortement associés aux événements cliniques que les paramètres cliniques et les paramètres échocardiographiques standards. Conclusions: Les fonctions réservoir, conduit et pompe de l'OG par STE étaient affectées dans la MF. La TRE a permis d'améliorer la fonction de l'OG. Les paramètres de déformation de l'OG étaient associés à la survenue de fibrillation auriculaire et d'accidents vasculaires cérébraux.
Background: Fabry disease (FD) is characterized by the accumulation of sphingolipids in multiple organs including the left atrium (LA). It is uncertain if the LA reservoir, conduit and contractile functions evaluated by speckle-tracking echocardiography are affected in Fabry cardiomyopathy and whether enzyme replacement therapy can improve LA function. Methods: In this retrospective cohort study, LA strain, strain rates and phasic LA volumes were studied in 50 FD patients and compared to 50 healthy controls. Results: All three LA phasic functions were altered. The peak positive strain (reservoir function) was 38.9 ± 14.9 % vs. 46.5 ± 10.9 % (p=0.004) and the late diastolic strain (contractile function) was 12.6 ± 5.9 % vs. 15.6 ± 5.3 % (p=0.010). In 15 patients who started enzyme replacement therapy during the study, most of the LA parameters improved at one-year follow-up (peak positive strain from 32.0 ± 13.5 % to 38.0 ± 13.5 %; p=0.006) whereas there was a trend towards deterioration in 15 patients who never received treatment (peak positive strain from 47.3 ± 10.8 % to 41.3 ± 9.3 %; p=0.058). Nine FD patients (21%) experienced new-onset atrial fibrillation or stroke during four-year follow-up. By univariate analysis, peak positive strain and early diastolic strain demonstrated significant associations with clinical events, surpassing conventional echocardiographic parameters and clinical characteristics. Conclusions: Left atrial reservoir, conduit and contractile functions by speckle-tracking echocardiography were all affected in FD. Enzyme replacement therapy improved LA function. Left atrial strain parameters were associated with atrial fibrillation and stroke.