Background

The role of an implantable cardioverter-defibrillater (ICD) in patients with symptomatic nonischemic heart failure was the subject of clinical trials. Although meta-analysis has shown a survival benefit for primary prevention ICD in this patient cohort, no randomized trials could demonstrate a significant reduction in all-cause mortality. Recently, the Danish trial did not show a significant reduction of cardiac mortality by ICD implantation. In this context, the present study aims to investigate prognosis in patients with nonischemic cardiomyopathy (CMP) undergoing prophylactic ICD placement.  

Methods and Results

We enrolled 166 consecutive patients (male 66%; mean age 68 ± 13.8 years) with nonischemic CMP admitted for primary prevention ICD implantation. Nonischemic CMP was defined by the absence of ischemic Late Gadolinium Enhancement (LGE) on cardiac MRI (CMR) and absence of 50 percent or more luminal stenosis on coronary angiography. The primary endpoints were all-cause mortality, cardiac mortality including adequate ICD discharge and any form of ICD therapy. Patients were divided into two groups defined by the presence/absence of LGE. From these two groups we assessed baseline characteristics and scar pattern by CMR prior to prophylactic ICD implantation and analyzed clinical outcomes.

LGE was present in 69 patients (41%; mean age 69.2 ± 13.3 years), showing a severe reduced ejection fraction (EF 24.01 ± 7.5%) with a myocardial scar burden of 4.1 ± 6.1 cm³. Median follow-up time was 4.8 years. There was no significant difference between the two groups regarding all-cause mortality (3 vs. 3; p= 0.695). Ventricular tachycardia was observed in 27 patients with LGE (p<0.001) and 15 patients with LGE suffered from ICD discharge (OR=4.16; 95% CI 1.52-11.38; p= 0.004). Cardiac mortality, including adequate ICD discharge was observed in 13 patients of the LGE group (OR 4.22; 95% CI 1.42-12.48; p=0.01).

Conclusion

Using a definition of nonischemic CMP that combines tissue characterization by CMR and anatomic absence of coronary stenosis by angiography, nonischemic LGE is still a strong predictor of cardiac mortality.