Increased AAI mode pacing threshold after termination of atrial fibrillation by acute administration of disopyramide phosphate.
OBJECTIVE
We studied changes in atrial pacing threshold after termination of atrial fibrillation (AF) by acute administration of disopyramide phosphate (DP) to elucidate the suitable setting for atrial pacing output before AF termination.


RESULTS
Four patients with sick sinus syndrome implanted with AAI mode pacemakers were examined. Disopyramide phosphate (2 mg/kg body weight) was injected intravenously for termination of a total of eight AF episodes. The maximal pacing threshold after AF termination (5.2+/-0.8 V at 0.45 ms) was significantly higher than that at baseline (1.3+/-0.2 V at 0.45 ms; P<0.01) and the average increment was 433+/-68%. During a period free from AF, an acute administration of DP did not increase the atrial pacing threshold and serum disopyramide levels were not toxic.


CONCLUSIONS
The increased atrial pacing threshold observed after AF termination cannot be explained by the action of DP alone. However, our results suggest that atrial pacing output should be set at the maximum value before DP is administered to induce AF termination in patients with AAI pacemaker-dependent bradyarrhythmias.
Anzawa
R
R
Division of Cardiology, Department of Internal Medicine, Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan. anzawar@jikei.ac.jp
Ishikawa
S
S
Tanaka
Y
Y
Okazaki
F
F
Mochizuki
S
S
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004206:Disopyramide / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012804:Sick Sinus Syndrome / Q000188:drug therapy / Q000503:physiopathology; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D004206:Disopyramide