Effect of oral verapamil on ventricular irregularity in long-standing atrial fibrillation.

In patients with chronic atrial fibrillation (AF), symptoms and cardiac function may be improved by regularizing the ventricular rhythm, even though the AF persists. This study concerned effects of i.v. and oral verapamil (V) on ventricular regularity. A regularizing effect was observed in 5 out of 10 patients after 0.15 mg of V/kg b.wt.i.v., but in only one patient after 80 mg of V By mouth. V in a dose of 240 mg by mouth resulted in ventricular regularity in 6 out of 10 other patients, 320 mg in a further 2 and 400 mg in the remaining 2 patients. Six patients were given chronic oral therapy in progressively increasing doses. Although ventricular regularity and symptom relief were obtained, intolerable side-effects precluded the evaluation of subjective long-term effects of this therapy in all but one patient. Further investigations, particularly concerning the pharmacokinetic mechanisms of V, are needed before the treatment can be recommended for patients with chronic AF.