Apparent protective effect of increased left ventricular wall thickness in an ICD population.
BACKGROUND
Expanding indications for the implantable cardioverter defibrillator (ICD) call for further enhancement of patient selection for optimization of use. Because a subgroup of patients who receive ICDs may not receive therapies, we sought to identify clinical predictors of therapy-free survival in ICD patients.


METHODS
We performed an analysis of a single-center, 13-year ICD implantation experience (1990-2002). The association between therapy-free survival and several clinical variables was evaluated.


RESULTS
From a total of 562 patients included in the database, 98 patients (17%) received no shock therapies or antitachycardia pacing (group A). When compared with a randomly selected sample of 131 patients who did receive ICD therapies (group B), there were no significant differences in age, gender, frequency of coronary artery disease, or extent of left ventricular (LV) dysfunction. However, left ventricular hypertrophy (LVH; increased wall thickness by echocardiography) was significantly more common in group A versus group B (30% versus 18%; Pearson's chi-square=4.69, P=.03). The odds of patients in group A having LVH were 1.98 times higher versus group B (95% confidence interval for odds ratio: 1.06-3.71). Comparisons of calculated mean LV mass between the 2 groups were not significantly different (group A 283+/-112 gm versus group B 271+/-108, P=.58). The overall mortality rate was 17% in group A and 22% in group B (P=.29).


CONCLUSIONS
Increased LV wall thickness was a significant, independent predictor of therapy-free survival in this ICD population. Because LV mass was unchanged, this finding may reflect the importance of LV dilation and wall thinning (ie, eccentric remodeling) as a risk factor for recurrent ventricular arrhythmia in ICD patients.
Division of Cardiology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
Vivek
V
Dogra
Ronald
R
Oliver
Jodi
J
Lapidus
Seshadri
S
Balaji
Jack
J
Kron
John
J
McAnulty
Sumeet S
SS
Chugh
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D017147:Defibrillators, Implantable; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography
D000889:Anti-Arrhythmia Agents