Sequential bilateral bundle branch block during dofetilide, a new class III antiarrhythmic agent, in a patient with atrial fibrillation.
BACKGROUND
The mechanism of wide QRS complex tachycardias during dofetilide infusion was studied in a patient with atrial fibrillation.


RESULTS
Endocardial recordings from the intraventricular conduction system showed that dofetilide caused "classic" aberrant conduction (Ashman phenomenon, typical QRS morphology) at high prematurity ratios (preceding interval = 1.78 x coupling interval--290), thus mimicking ventricular ectopy. In addition, there was frequent sequential bilateral bundle branch block, caused by a significant difference in preceding bundle-to-bundle intervals (mean difference +/- 1 SD: 74 +/- 26 msec).


CONCLUSIONS
The present findings may prove helpful in the clinical assessment of wide QRS complex rhythms after dofetilide and possibly other "pure" Class III antiarrhythmics.
Crijns
H J
HJ
Department of Cardiology, Thoraxcenter, University Hospital, Groningen, The Netherlands.
Kingma
J H
JH
Gosselink
A T
AT
Dalrymple
H W
HW
De Langen
C D
CD
Lie
K
K
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000188:drug therapy* / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000139:chemically induced*; D004562:Electrocardiography; D006329:Heart Conduction System / Q000187:drug effects; D006801:Humans; D008297:Male; D010627:Phenethylamines / Q000009:adverse effects*; D013449:Sulfonamides / Q000009:adverse effects*
D000889:Anti-Arrhythmia Agents; D010627:Phenethylamines; D013449:Sulfonamides; C063533:dofetilide