Triphasic time dependence of prognostic markers in patients with sustained ventricular tachyarrhythmias and coronary artery disease.

To characterize the time dependence of prognostic markers for arrhythmia recurrence and arrhythmic death, 81 consecutive patients with documented sustained ventricular tachycardia (VT) or fibrillation (VF) and coronary artery disease (CAD) were analyzed. During follow-up, 28 patients had arrhythmia recurrence and 15 patients had sudden or arrhythmic death. Three different hazard phases were identified by fitting piece-wise exponential function curves to the distribution of both arrhythmia recurrence and sudden/arrhythmic death. An initial phase (0 to 6 months) had an arrhythmia recurrence rate of 2.1% per month; a second low-risk phase (6 to 38 months) had a rate of 0.88%; and a late high-risk phase (greater than 38 months) had a rate of 2.2%. Sudden/arrhythmic death rates in each phase were 1.1%, 0.41%, and 1.7% per month, respectively. Separate Cox regression analyses within each phase identified the following independent predictors of arrhythmia recurrence: in the early phase, ejection fraction (EF) (p = 0.033) and VT inducibility rank (p = 0.048); and in the late phase, VT inducibility rank only (p = 0.003). Likewise, independent predictors of sudden/arrhythmic death were: in the early phase, EF (p = 0.049); and in the late phase, VT inducibility rank (p = 0.008) and previous history of congestive heart failure (p = 0.032). In CAD patients with documented sustained VT/VF, the probabilities of arrhythmia recurrence and sudden/arrhythmic death each followed a similar triphasic hazard function. Highest risk occurred in the late phase and the VT inducibility rank was predictive of late phase events, while EF was a predictor of early phase events.