EFFECT OF PROPHYLACTIC ANTIARRHYTHMIC THERAPY ON TIME TO IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR DISCHARGE IN PATIENTS WITH VENTRICULAR TACHYARRHYTHMIAS

Implantable cardioverter-defibrillators (ICDs) are being used increasi ngly for treatment of malignant ventricular tachyarrhythmias. However, ICD discharge is associated with significant morbidity. Antiarrhythmi c therapy could reduce the frequency of ICD discharge, but its effect is uncertain. Thus, the effect of antiarrhythmic therapy was evaluated in a randomized trial. Thirty-four patients (32 men and 2 women, aver age age 60 years) who received an ICD for sustained ventricular tachyc ardia or fibrillation were entered in the trial and randomized to the best ''drug'' therapy (group 1; n = 17) or no therapy (group 2; n = 17 ). After the first ICD discharge, patients were to be crossed over to the alternative treatment arm. Twenty nine patients had coronary arter y disease. The induced arrhythmia was ventricular tachycardia in 33 pa tients and ventricular fibrillation in 1. Ejection fraction averaged 3 9%. The 2 groups were well balanced, without differences in demographi c variables. In group 1, class I therapy was given to 9 patients and c lass III to 9. Beta blockade was used in a similar number of patients in groups 1 and 2 (n = 8 and 6, respectively). Time to the first shock or the end of follow-up averaged 143 days (range 1 to 609). During fo llow-up, 21 patients had a first ICD discharge event (11 in group 1, a nd 10 in group 2; p = 0.72). Event-free survival in each group was ass essed by the Kaplan Meier method, using the intention-to-treat approac h. Overall median time to the first event was 134 days. Time to the fi rst event did not differ between groups (p = 0.66; log-rank test). The effect of drug therapy versus no therapy was also compared in 13 pati ents who underwent crossover treatment. In the crossover analysis, eve nt-free survival was also similar for the 2 treatment arms (p = 0.51; log-rank test). Individual responses in 6 patients showed substantial (greater than threefold) differences in time to the discharge event be tween treatment arms, which favored the drug in 4 and no drug in 2 (p = NS). The results of this initial randomized experience do not suppor t routine, adjunctive antiarrhythmic therapy for the purpose of extend ing the time to ICD discharge. Additional and larger studies are indic ated. It is recommended currently that the use of antiarrhythmic drugs in the setting of ICD therapy should be based on individual patient n eeds.