Circadian variation in the occurrences of ventricular tachyarrhythmias: Differences between coronary artery disease and dilated cardiomyopathy

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. 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 . 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 R² = 0.854 with harmonic and R² = 0.767 with polynomial model. Similarly with DCM patients, fitting with polynomial model led to R² = 0.997 while harmonic regression led to R² = 0.983. Different modes of VT onset show strongly different circadian patterns even when patients have the same etiology. Circadian distribution of VT episodes from CAD and DCM patients are intrinsically different.