ASSOCIATION BETWEEN EASE OF SUPPRESSION OF VENTRICULAR ARRHYTHMIA ANDSURVIVAL

Background We tested the hypothesis that patients whose ventricular ar rhythmias are easy to suppress have a lower rate of arrhythmic death, defined as arrhythmic death and nonfatal cardiac arrest, the primary e nd point in the Cardiac Arrhythmia Suppression Trials (CAST-I and CAST -II), than patients whose ventricular arrhythmias are hard to suppress . In addition, we evaluated the association between ease of suppressio n of ventricular arrhythmias and mortality of all causes. Methods and Results CAST-I investigated the effect on arrhythmic death of ventricu lar premature depolarization (VPD) suppression achieved by three drugs , encainide, flecainide, and moricizine, at two different dose levels; CAST-II investigated the same effect, using moricizine alone at three dose levels. If suppression was achieved, patients were randomized to the effective active drug or corresponding placebo. To examine the in dependence of easily suppressed ventricular arrhythmias as a predictor of arrhythmic death, we adjusted statistically for other variables th at were related both to ease of suppression and arrhythmic death. Pati ents with ventricular arrhythmias (n=1778) that were easy to suppress had fewer arrhythmic deaths during follow-up than those with ventricul ar arrhythmias that were hard to suppress (n=1173) (relative risk, .59 ; P=.003). Patients whose VPDs were easily suppressed were older and h ad a lower frequency of prior history of heart failure and myocardial infarction. They also had a higher incidence of anterior myocardial in farction, VPD frequency, and average ejection fraction. After adjustin g for these variables, we found that easily suppressed ventricular arr hythmias were still significant predictors of arrhythmic death (relati ve risk, 66; P=.013). Conclusions This study shows that the ease of VP D suppression identifies a subgroup of postmyocardial infarction patie nts who have low risk of arrhythmic death.