Electrophysiologic effects and long-term efficacy of bepridil for recurrent supraventricular tachycardias.

Thirteen patients underwent electrophysiologic evaluation for recurrent supraventricular tachycardia (SVT). The effects of intravenous bepridil (4 mg/kg) were evaluated during the initial study in 5 patients, and 12 patients underwent repeat study 7 to 10 days later taking oral bepridil, 300 to 400 mg/day. Intravenous bepridil increased the pacing cycle length inducing atrioventricular (AV) (276 +/- 43 vs 334 +/- 31 ms, p less than 0.01) and ventriculoatrial (VA) block (268 +/- 34 vs 310 +/- 35 ms, p less than 0.001), the retrograde refractory period of the accessory pathway (251 +/- 17 vs 295 +/- 25 ms, p less than 0.05) and the ventricular refractory period (216 +/- 17 vs 226 +/- 11 ms, p less than 0.05), and prevented induction of sustained SVT in 3 patients. Oral bepridil increased the sinus cycle length (723 +/- 64 vs 800 +/- 118 ms, p less than 0.05), corrected QT (403 +/- 14 vs 431 +/- 21 ms, p less than 0.05) and the pacing cycle inducing AV (288 +/- 63 vs 353 +/- 78 ms, p less than 0.01) and VA block (271 +/- 31 vs 408 +/- 124 ms, p less than 0.01). It prolonged the refractory period of the atrium (195 +/- 29 vs 233 +/- 36 ms, p less than 0.05), AV node (264 +/- 35 vs 303 +/- 22 ms, p less than 0.05), ventricle (221 +/- 16 vs 245 +/- 21 ms, p less than 0.01), accessory pathway in the AV (290 +/- 47 vs 329 +/- 54 ms, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)