Turbulence and deceleration capacity of the heart rate in patients with coronary artery disease and implanted cardioverter defibrillator

Abstract

Aim. To study the possibility of using of heart rate turbulence (HRT) and deceleration capacity (DC) in the risk stratification of fatal events in patients with coronary artery disease (CAD) and implanted cardioverter defibrillator (ICD). Material and methods. The study included 45 patients with sinus rhythm and verified CAD, who had indications for ICD. A 24-hour ECG monitoring was performed with the evaluation of non-invasive predictors of sudden cardiac death. The minimum observation period was 30 months (the average observation period was 48 (42;51) months). Two endpoints were assessed: the onset of deaths and the justified ICD actuations. Results. During the observation period, 10 patients died (5 from progression of heart failure, 2 from recurrent myocardial infarction, 2 from non-cardiac pathology, and 1 died suddenly before implantation of a defibrillator). Arrhythmic events occurred in 13 people. Compared to the surviving patients, deceased patients’ mean DC value was significantly lower (1,25 (0,48;2,23) ms vs 3,3 (1,85;5,40) ms, p=0,016). There were significantly more frequent DC in the high-risk zone (80% vs 34%, p=0,024) and type 2 HRT disorders (80% vs 29%, p=0,009). When comparing patients with arrhythmic events and without them, no significant differences in DC and HRT were detected. According to univariate regression analysis, HRT and DC were risk factors for death (p=0,004 and p=0,006, respectively). Conclusion. Electrophysiological markers reflecting vegetative imbalance (HRT and DC) in patients with CAD and ICD can identify patients with high risk of overall mortality, but it is not associated with the risk of ventricular tachyarrhythmias development.