Chronic flecainide therapy selected by electrophysiology testing of intravenous flecainide

Abstract The utility of flecainide acetate was evaluated in 93 patients by means of electrophyslologic studies before and affer intravenous flecainide administration to determine long-term efficacy. Twenty patients had a prior history of at least one cardiac arrest and 73 patients had sustained ventricular tachycardia (VT). The mean radionuclear ejection fraction was 32 ± 5%. Flecainide was evaluated in 93 patients, with 44 patients no longer having VT following flecainide (47% efficacy). Procainamide was evaluated in 69 patients; 24 patients had an adverse reaction to procainamide and 28 of the 69 patients were protected on procainamide (40% efficacy). The mean serum concentration of flecainide achieved in the protected group was 298 ± 36 ng/ml and 4.3 μg/ml for procainamide. Both fleccainide and procainamide significantly prolonged refractoriness, lengthened QRS duration, while only procainamide increased the QT interval. All 93 patients were discharged on antiarrhythmic therapy, 42 on flecainide, 27 on other antiarrhythmic therapy guided by electrophyslologic testing, and 24 on amiodarone (when all other agents falled). Six of the 42 patients on flecainide complained of adverse side effects, but none were severe enough to warrant stopping therapy. Of the 42 patients on flecainide, four (9%) died suddenly over 18 ± 4 months. Twenty-seven patients were on other therapy; eight of these have died, three suddenly (11%), four with myocardial infarctions, and one due to congestive heart failure. Twenty-four patients started amiodarone; 11 have died, five (21%) suddenly, four of congestive heart failure, one of pulmonary fibrosis, and one with myocardial infarction. While receiving the acute intravenous administration of flecainide, seven patients developed spontaneous sustained VT (serum level 357 ± 72 ng/ml). Two episodes eventually terminated spontaneously, one required defibrillation, while four patients falled defibrillation but responded to lidocaine. Evaluation with electrophysiologic testing of flecainide administered intravenously appears to predict successful chronic therapy. Flecainide appears well tolerated both intravenously and orally, but does possess a significant incidence of arrhythmogenicity.