Evaluating predictors of appropriate
implantable cardioverter-defibrillator (ICD)
therapy in patients with
idiopathic dilated cardiomyopathy (IDC) may be helpful in developing risk stratification strategies for these patients. Fifty-four patients with IDC underwent ICD implantation and were followed up. Twenty-three patients (42%) had a class I indication for ICD implantation; the remaining patients underwent implantation for multiple risk factors for
sudden death including
left ventricular dysfunction,
nonsustained ventricular tachycardia,
syncope, or positive electrophysiologic study results. Clinical, electrocardiographic, and electrophysiologic data were collected. Appropriate ICD
therapy was defined as an antitachycardia pacing
therapy or
shock for
tachyarrhythmia determined to be either
ventricular tachycardia or
ventricular fibrillation. Appropriate ICD
therapy was observed in 23 patients (42%). There was a significant difference in use of beta-blocker
therapy between patients who did and did not have appropriate ICD
therapy (p <0.0003). Cox regression analysis identified the following univariate predictors (p <0.1): class I indication (p <0.005) and lack of use of beta-blocker
therapy (p <0.0007). In multivariate analysis, only lack of beta-blocker use (relative risk 0.15, 95% confidence intervals 0.05 to 0.45; p <0.0007) was identified as a predictor of appropriate ICD
therapy. Of the patients who received ICD
therapy, only 4 (17%) were taking beta blockers, whereas 21 of the 31 patients (68%) who did not receive ICD
therapy were treated with beta blockers (p <0.0003). In patients with IDC selected for ICD implantation, the most consistent predictor of appropriate ICD
therapy was lack of beta-blocker use. Attempts should be made to administer beta blockers to these patients, if tolerated.