Slowing of ventricular tachycardia as a possible endpoint for serial drug testing at electrophysiological study.

Certain patients who cannot be rendered noninducible by serial drug testing during electrophysiology study demonstrate significant slowing of their ventricular tachycardia rate with selected agents. We evaluated the characteristics and outcome of 19 such patients to assess whether this slowing could be considered an acceptable endpoint for treatment. This group consisted of 14 males and 5 females (mean age 63 +/- 9) with a mean ejection fraction of 28 +/- 13% and inducible sustained ventricular tachycardia. Sixteen patients had known coronary artery disease and 13 had prior myocardial infarction. The other three patients had idiopathic cardiomyopathy. Serial drug testing during an electrophysiology protocol that used up to three extrastimuli at two or three cycle lengths at two right ventricular sites was used to select a medication regimen that provided optimal ventricular tachycardia slowing without limiting side effects. Five patients were treated with amiodarone, three with Ic agents (all with ejection fraction greater than 30%), and the remainder with Ia and Ib agents alone or in combination. Mean initial ventricular tachycardia rate was 219 +/- 26 beats/min with posttreatment ventricular tachycardia rate 137 +/- 17 (mean initial cycle length 278 +/- 35 msec, posttreatment 443 +/- 53 msec). Two groups were identified, those who had recurrent (although well-tolerated) ventricular tachycardia (group I, n = 8, mean time to recurrence = 15 months), and those who did not (group II, n = 11, mean follow-up 22 months). Overall sudden death rate was 5%, while total mortality was 11% (all mortality in group I).(ABSTRACT TRUNCATED AT 250 WORDS)