Long-term outcome in patients who survive out of hospital ventricular fibrillation and undergo electrophysiologic studies: Evaluation by electrophysiologic subgroups

AbstractThe long-term outcome of 241 survivors of out of hospital ventricular fibrillation who underwent programmed electrical stimulation was evaluated. Patients were categorized according to the rhythm induced at baseline drug-free electrophysiologic testing. Ventricular fibrillation was induced in 39 (16%) (Group 1), sustained ventricular tachycardia in 66 patients(27%) (Group 2) and nonsustained ventricular tachycardia in 34patients (14%) (Group 3); 102 patients (42%) (Group 4) did not have an arrhythmia inducible at baseline electrophysiologic testing. Antiarrhythimic drugs were administered over the long term to 92% of patients in Group 2, 91% of patients in Group 1 and 47% of patients in Group 4. At a mean follow-uptime of 30 ± 15 months, recurrent sudden cardiac death or nonfatal ventricular fibrillation occurred in 11 (28%) of 39 patients with inducible ventricular fibrillation (Group 1), 14 (21%) of 66 patients with inducible sustained ventricular tachycardia (Group 2), 4 (12%) of 34 patients with inducible nonsustained ventricular tachycardia (Group 3) and 16 (16 %) of 102 patients without inducible arrhythmias (Group 4). Actuarial analysis revealed a 2 year cumulative arrhythmia-free survival rate of 65% for patients in Group 2, 71% for patients in Group 1, 79% for patients in Group 3 and 81% for patients in Group 4 (p = 0.02).Actuarial survival of patients with inducible sustained ventricular tachycardia or ventricular fibrillation suppressed by electrophysiologically guided drug therapy was not significantly different from that in patients whose arrhythmia was not suppressed. Multivariate regression analysis revealed that only the presence of congestive heart failure was an indepeedent predictor of outcome in these patients. The prognostic significance of inducibility at baseline electrophysiologic testing in survivors of ventricular fibrillation is dependent on the status of their left ventricular function and does lot independently predict poor outcome. Patients with inducible sustained ventricular tachycardia or ventricular fibrillation that was subsequently randered noninducible by electrophysiologically guided drug therapy with class I antiarrhythmic drugs did not have an improved survival rate compared with that of patients whose tachyarrhythmia could not be suppressed