Predictors of Appropriate Implantable Cardioverter Defibrillator (ICD) Therapy in Primary Prevention Patients with Ischemic and Nonischemic Cardiomyopathy

Background: We sought to assess predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients receiving primary prevention ICDs. Methods: Four hundred twenty-one consecutive patients (ischemic and nonischemic) undergoing primary prevention ICD implantation were studied. Patients were grouped based on the presence/absence of appropriate ICD therapy. Summary data and stored electrograms from ICDs were reviewed to determine appropriateness of therapy. Predictors of therapy were assessed by both univariate and multivariate Cox regression analysis. Results: Of 421 primary prevention patients undergoing ICD implantation, 79 (19%) had received appropriate ICD therapies. By univariate comparison, nonsustained ventricular tachycardia (NSVT), male sex, left ventricle diastolic diameter (LVDD), and hypertension were all significant predictors for ICD therapy over a mean follow-up time of 751 +/- 493 days (P <= 0.05). The use of beta-blockers was found to be a negative predictor. In the ischemic cardiomyopathy (ICM) population, 55 (17%) patients received ICD therapy and this was predicted by NSVT, hypertension, LVDD, and left atrial diameter. beta-blockers were protective. In the nonischemic dilated cardiomyopathy (NIDCM) population, 24 (23%) received appropriate therapies, which were predicted by NSVT, male sex, dual chamber device, lack of biventricular device, and lack of beta-blockers. By multivariate analysis, NSVT, hypertension, and lack of beta-blockers were significant for ICM, while NSVT and absence of beta-blockers were predictive for NIDCM. Ejection fraction, New York Heart Association class, and QRS width were not significantly different between therapy and no-therapy groups in any population. Conclusions: ICD-delivered therapy occurred in 19% of primary prevention patients with both ischemic and dilated cardiomyopathy and was predicted by NSVT and a lack of beta-blocker use. (PACE 2010; 33:320-329)