Efficacy of flecainide in pacing-induced sustained ventricular tachyarrhythmias: correlation to clinical parameters and tachycardia-characteristics

Abstract

Seventy-two patients with sustained ventricular tachycardia or syncope of unknown origin underwent electrophysiologic evaluation before and after therapy with flecainide (200-300 mg day-1). In all patients, sustained ventricular tachycardia or ventricular fibrillation was inducible during control electrophysiologic study. During flecainide therapy, sustained ventricular tachycardia (VT) was no longer inducible in 18 patients (25%) whereas in 54 patients, VT was still inducible. In five of the latter patients, VT became more difficult to induce (overall efficacy 32%). The rate of VT decreased from 214 +/- 49 beats min-1 during the control electrophysiologic study to 178 +/- 48 beats min-1 during flecainide (P less than 0.01). The ERP of the right ventricle increased from 251 +/- 27 ms during the control study to 267 +/- 34 ms on flecainide (P less than 0.01). Mean ejection fraction and mean LVEDP did not differ between responders and non-responders, yet the presence of a left ventricular aneurysm correlated with a lack of antiarrhythmic response to flecainide. VT rate as well as VT morphology during the control study discriminated between responders and non-responders; 11% of patients with VT-rate less than or equal to 230 beats min-1 responded to oral flecainide compared with 31% with a VT rate greater than 230 beats min-1 at control. 26% with induced monomorphic VT responded, compared with 100% with induced VF during the control study. 18 of 23 responders were discharged on flecainide. During a mean follow-up of 26 +/- 18 months, two patients experienced a recurrence of VT and in one patient, flecainide had to be discontinued due to side-effects.(ABSTRACT TRUNCATED AT 250 WORDS)