Electrophysiologic effects and therapeutic efficacy of intravenous flecainide for termination of paroxysmal supraventricular tachycardia.

Flecainide is a class IC antiarrhythmic agent with a controversial role in the treatment of ventricular arrhythmias following myocardial infarction after the publication of the Cardiac Arrhythmia Suppression Trial (CAST). To assess its utility in paroxysmal supraventricular tachycardia (PSVT), we evaluated the electrophysiologic effects and therapeutic efficacy of intravenous flecainide, administered in a dose of 2 mg per kg body weight in 26 patients of PSVT, studied by programmed electrical stimulation. The patients' age ranged from 18-49 years (mean: 27 +/- 8) and none had organic heart disease. The mechanism of PSVT was atrioventricular nodal reentry (AVNRT) with anterograde conduction through slow pathway and retrograde through fast pathway in 14, and atrioventricular reentry (AVRT) utilizing an accessory pathway in 12 patients. Flecainide was successful in terminating the tachycardia in all (100%) patients of AVNRT and 11 (92%) patients with AVRT. In both the types, the tachycardia was terminated by selective block in conduction through the retrograde limb of the reentry circuit. The drug also produced a complete anterograde block with abolition of preexcitation in 6 out of 8 patients with WPW syndrome. After the drug, the tachycardia was reinducible in one patient of AVNRT and 4 with AVRT. The cycle length of inducible tachycardia increased from 295 +/- 25 ms to 389 +/- 24.5 ms after flecainide (p < 0.001). There were no adverse haemodynamic effects of the drug. Our results, thus, showed that intravenous flecainide is a highly effective and safe antiarrhythmic drug for termination of PSVT mediated by atrioventricular nodal and atrioventricular reentry mechanisms without producing any adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)