Use of ibutilide in cardioversion of patients with atrial fibrillation or atrial flutter treated with class IC agents.
OBJECTIVE
We sought to assess the efficacy and safety of ibutilide cardioversion for those with atrial fibrillation (AF) or atrial flutter (AFL) receiving long-term treatmentwith class IC agents.


BACKGROUND
Attenuation of ibutilide-induced QT prolongation has been observed in a small number of patients pretreated with class IC agents. The clinical significance of the interaction between ibutilide and class IC agents is unknown.


METHODS
Seventy-one patients with AF (n = 48) or AFL (n = 23), receiving propafenone 300 to 900 mg/day (n = 46) or flecainide 100 to 300 mg/day (n = 25), presented for ibutilide (2.0 mg) cardioversion.


RESULTS
The mean durations of arrhythmia episode and arrhythmia history were 25 +/- 48 days and 4.4 +/- 6.4 years, respectively. Sixty-five patients (91.5%) had normal left ventricular systolic function. Twenty-three of 48 patients (47.9%; 95% confidence interval, 33.3% to 62.8%) with AF and 17 of 23 patients (73.9%; 95% confidence interval, 51.6% to 89.8%) with AFL converted with mean conversion times of 25 +/- 14 min and 20 +/- 12 min, respectively. There was a small increase in corrected QT interval after ibutilide (from442 +/- 61 ms to 462 +/- 59 ms, p = 0.006). One patient developed non-sustained polymorphous ventricular tachycardia and responded to intravenous magnesium. Another developed sustained torsade de pointes and was treated effectively with direct-current shock and intravenous dopamine.


CONCLUSIONS
Our observations suggest that the use of ibutilide in patients receiving class IC agents is as successful in restoring sinus rhythm and has a similar incidence of adverse effects as the use of ibutilide alone.
Hongo
Richard H
RH
University of California, San Francisco 94143-1354, USA.
Themistoclakis
Sakis
S
Raviele
Antonio
A
Bonso
Aldo
A
Rossillo
Antonio
A
Glatter
Kathryn A
KA
Yang
Yanfei
Y
Scheinman
Melvin M
MM
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D001282:Atrial Flutter / Q000188:drug therapy* / Q000503:physiopathology; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D004554:Electric Countershock; D004562:Electrocardiography; D005260:Female; D005424:Flecainide / Q000008:administration & dosage; D006329:Heart Conduction System; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D011405:Propafenone / Q000008:administration & dosage; D011446:Prospective Studies; D012495:San Francisco; D013449:Sulfonamides / Q000008:administration & dosage*; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide; D011405:Propafenone; D005424:Flecainide