Circadian Variation in the Occurrences of Ventricular Tachyarrhythmias: Differences between Coronary Artery Disease and Dilated Cardiomyopathy.

Aim: This study investigates circadian distribution of ventricular tachyarrhythmias (VT) in coronary artery disease (CAD) and dilated cardiomyopathy (DCM) patients that received an implantable cardioverter defibrillator (ICD) as secondary prevention. Methods: 37 patients are studied. Times of VT episode are retrieved from data log of the ICD; the analysis includes the separation of different modes of VT-onset. Circadian distributions are fitted using harmonics and polynomial regression models; Goodness of fit is estimated using the coefficient of determination R 2 . Results: 165 VT episodes are recorded from 37 patients: 79 are collected from 26 CAD and 86 from 11 DCM patients. Fitting of the circadian distribution of CAD population gives R 2 =0.854 with harmonic and R 2 =0.767 with polynomial model. Similarly with DCM patients, fitting with polynomial model led to R 2 =0.997 while harmonic regression led to R 2 =0.983. Different modes of VT onset show strongly different circadian patterns even when patients have the same etiology. Conclusion: Circadian distribution of VT episodes from CAD and DCM patients are intrinsically different.