Effects of verapamil and ibutilide on atrial fibrillation and postfibrillation atrial refractoriness.
BACKGROUND
Early recurrence of atrial fibrillation (AF) after cardioversion may be related to shortening of the atrial effective refractory period (ERP). This study compared the effects of verapamil and ibutilide on AF cycle length (AFCL), atrial ERP, and susceptibility to recurrent AF.


RESULTS
In 33 adults, the atrial ERP was measured at basic drive CLs of 350 and 500 msec before and after a brief episode of pacing-induced AF. During AF, verapamil, ibutilide, or saline was infused in 11 patients each. Shortening of the post-AF atrial ERP was attenuated by verapamil and prevented by ibutilide. AFCL shortened by 32+/-21 msec in the verapamil group (P < 0.01), prolonged by 44+/-14 msec in the ibutilide group (P < 0.001), and did not change in the control group. AF converted to sinus rhythm within 10 minutes less often after verapamil (0%) than after ibutilide (82%) or than in the control group (73%). Post-AF, AF lasting > 10 minutes was induced more often in the verapamil group than in the ibutilide group (26% vs 0%; P = 0.01). Another 10 patients received verapamil or ibutilide in the absence of AF. Atrial ERP was unchanged after verapamil and prolonged after ibutilide.


CONCLUSIONS
Verapamil shortens AFCL and impedes the conversion of induced AF, whereas ibutilide prolongs AFCL and does not impede the early conversion of induced AF. Ibutilide is more effective than verapamil in preventing pos
Sticherling
Christian
C
Department of Internal Medicine II, Free University of Berlin, Germany.
Hsu
William
W
Tada
Hiroshi
H
Bares
Anton C
AC
Oral
Hakan
H
Pelosi
Frank
F
Knight
Bradley P
BP
Strickberger
S Adam
SA
Morady
Fred
F
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D016009:Chi-Square Distribution; D005260:Female; D006325:Heart Atria / Q000187:drug effects / Q000503:physiopathology; D006801:Humans; D008297:Male; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D013449:Sulfonamides / Q000627:therapeutic use*; D016896:Treatment Outcome; D014700:Verapamil / Q000627:therapeutic use*
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide; D014700:Verapamil