Santinelli V, Turco P, De Paola M, Smimmo D, Giasi M, Santinelli C, Chiariello M, Condorelli M. University of Naples, Italy. Cardiovasc Drugs Ther 1990 Jun;4(3):681-5. We present our experience on the efficacy of propafenone in ten symptomatic patients with Wolff-Parkinson-White syndrome. The symptoms were dizziness in seven patients and syncope in three patients. While experiencing the symptoms, three of them presented an episode of atrial fibrillation, the shortest preexcited RR intervals being 140, 190, and 200 ms. In the other seven patients, the ECG was not recorded during the symptoms, but an episode of atrial fibrillation was subsequently induced by transesophageal pacing. The shortest preexcited RR intervals during induced atrial fibrillation were 180, 200, 270, 240, 230, 250, and 200 ms. Seven patients had both atrial fibrillation and supraventricular tachycardia. Propafenone (1-2 mg/kg) administered IV in only the patients with sustained atrial fibrillation (spontaneous in two and induced in one patient) prolonged the shortest preexcited RR intervals from 190, 200, and 180 ms to 340, 335, and 340 ms. In the other seven patients, propafenone was not given IV because atrial fibrillation rapidly deteriorated into ventricular fibrillation (one patient) or spontaneously reverted within 1-2 minutes to sinus rhythm (six patients). After oral propafenone, serial trans-esophageal pacing studies reinduced atrial fibrillation in 4 of 6 patients (the shortest preexcited RR intervals increased from 190, 180, 200, and 270 ms to 420, 320, 340, and 380 ms); only in one patient was it possible after propafenone to induce an atrial flutter without preexcitation. After propafenone therapy in 4 of 7 patients, supraventricular tachycardia was not inducible.