Electrophysiological effects of ibutilide in patients with accessory pathways.
BACKGROUND
Atrial fibrillation (AF) may cause life-threatening ventricular arrhythmias in patients with Wolff-Parkinson-White syndrome. We prospectively evaluated the effects of ibutilide on the conduction system in patients with accessory pathways (AP).


RESULTS
In part I, we gave ibutilide to 22 patients (18 men, 31+/-13 years of age) who had AF during electrophysiology study, including 6 pediatric patients </=18 years of age. Ibutilide terminated AF in 21 of 22 patients (95%) during or 8+/-5 minutes after infusion and prolonged the shortest preexcited R-R interval during AF. Successful ablation was performed in all patients. In part II, ibutilide was given to 18 patients (14 men, 28+/-21 years) to assess its effects on the AP and conduction system. Ibutilide prolonged the antegrade atrioventricular node effective refractory period (ERP) (from 252+/-60 to 303+/-70 ms; P<0.02). Ibutilide caused transient loss of the delta wave in 1 patient and abolished inducible tachycardia in 2 patients, although retrograde mapping still allowed for successful AP ablation. The antegrade AP ERP prolonged from 275+/-40 to 320+/-60 ms (P<0.01), as did the antegrade AP block cycle length; the retrograde AP ERP and block cycle length similarly prolonged with ibutilide. The relative and effective refractory period of the His-Purkinje system increased in 61% of patients after ibutilide. There were no adverse side effects.


CONCLUSIONS
We report the use of ibutilide in terminating AP-mediated AF, including the first report in the pediatric population. Ibutilide prolonged refractoriness of the atrioventricular node, His-Purkinje system, and AP.
Glatter
K A
KA
Cardiovascular Research Institute and Section of Adult and Pediatric Cardiac Electrophysiology, University of California, San Francisco, USA.
Dorostkar
P C
PC
Yang
Y
Y
Lee
R J
RJ
Van Hare
G F
GF
Keung
E
E
Modin
G
G
Scheinman
M M
MM
D000293:Adolescent; D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D006328:Cardiac Catheterization; D002304:Cardiac Pacing, Artificial; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects* / Q000503:physiopathology; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013449:Sulfonamides / Q000008:administration & dosage* / Q000009:adverse effects; D016896:Treatment Outcome; D014927:Wolff-Parkinson-White Syndrome / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide