QRS prolongation is associated with high defibrillation thresholds during cardioverter-defibrillator implantations in patients with hypertrophic cardiomyopathy.
BACKGROUND
Although high defibrillation threshold (DFT) is a major and unavoidable clinical problem after implantation of an implantable cardioverter defibrillator (ICD), little is known about the cause and management of a high DFT in patients with hypertrophic cardiomyopathy (HCM). The purpose of this study was to assess the predictors of a high DFT in patients with HCM.


RESULTS
Twenty-three patients with non-dilated HCM who underwent ICD implantation were included. The DFT at the time of the device implantation was measured in all patients. The patients were divided into 2 groups, a high DFT group (DFT >or=15J, n=13) and a low DFT group (DFT <15J, n=10); and their baseline characteristics were compared. The QRS duration was longer in the high than in the low DFT group (128 +/-31 vs 103 +/-12 ms, respectively; P=0.02). QRS duration, left ventricular (LV) end-systolic diameter, and LV ejection fraction were significant predictors of DFT in univariate analysis. However, in multivariate analysis, the only factor significantly associated with DFT was QRS duration (P=0.002).


CONCLUSIONS
QRS duration is the most consistent predictor of a high DFT in HCM patients undergoing ICD implantation.
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan.
Takayuki
T
Nagai
Takashi
T
Kurita
Kazuhiro
K
Satomi
Takashi
T
Noda
Hideo
H
Okamura
Wataru
W
Shimizu
Kazuhiro
K
Suyama
Naohiko
N
Aihara
Junjiro
J
Kobayashi
Shiro
S
Kamakura
D000293:Adolescent; D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology* / Q000628:therapy*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D014693:Ventricular Fibrillation / Q000503:physiopathology*; D055815:Young Adult