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INTRODUCTION AND OBJECTIVES: Hypertrophic cardiomyopathy (HCM) is accompanied by pathophysiological changes that predispose to the development of atrial fibrillation (AF). This arrhythmia impacts negatively on the morbidity, mortality and quality of life of these patients. Our objective was to evaluate the behavior of left atrial function, by means of atrial strain (derived from speckle tracking) and volumetric analysis by three-dimensional echocardiography, in patients with HCM with paroxysmal AF. METHOD: We analysed left atrial function in 53 patients with HCM, 25 of whom were paroxysmal AF carriers (mean age 61.7±9.9 years; 56% female) compared with 28 members of the control group (mean age 60.5±10 years; 53.6% female) who were matched especially for sex, age and other demographic data. RESULTS: It was observed that patients with HCM and a history of paroxysmal AF had lower left atrial emptying fractions than individuals in the control group; and the active atrial emptying fraction was a factor independently associated with the presence of this arrhythmia (p=0.018; odds ratio=0.93). Moreover, we found a significant reduction of the left atrial strain in all its components in the total sample of patients, with no difference between the groups. CONCLUSIONS: Measurements of atrial emptying fractions by three-dimensional echocardiography allowed differentiating patients with HCM with and without paroxysmal AF.
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OBJECTIVE: Risk stratification of sudden cardiac death in patients with coronary artery disease is of great importance. We evaluated the association between ventricular repolarization and induction of malignant ventricular arrhythmias on electrophysiological study of patients with coronary artery disease. METHODS AND RESULTS: A total of 177 patients (65±10.1 years, 83.6% male, mean left ventricular ejection fraction [LVEF] 37.5±13.6%) were analyzed. For each 10 ms increment in the QT interval, there was a 7% increase in malignant ventricular arrhythmias inducibility; QT cutoff point of 452 ms had an accuracy of 0.611 for predicting malignant ventricular arrhythmias (p=0.011). Male gender (odds ratio [OR]=4.18, p=0.012), LVEF <35% (OR=2.32, p=0.013), amiodarone use (OR=2.01, p=0.038), and prolonged QT (OR=1.07, p=0.023) were associated with malignant ventricular arrhythmias. In patients with ventricular dysfunction, QT >452 ms was associated with significantly increased risk of malignant ventricular arrhythmias (OR=5.44, p=0.0004). In those with LVEF ³35%, QT dispersion (QTd) was significantly higher in patients with inducible malignant ventricular arrhythmias. QTd >20 ms had 0.638 accuracy and 81.3% negative predictive value in predicting malignant ventricular arrhythmias. CONCLUSION: QT interval is an independent factor associated with malignant ventricular arrhythmias in patients with coronary artery disease. The combination of ventricular dysfunction and prolonged QT interval is associated with a 5.44-fold increase of malignant ventricular arrhythmias induction. Male gender, amiodarone use, and decreased left ventricular ejection fraction are also associated with increased risk of inducibility of malignant ventricular arrhythmias on the electrophysiological study.