Association between appropriate ICD therapy and myocardial infarction scar characteristics assessed by cardiac magnetic resonance imaging

Abstract

Purpose: We hypothesized that myocardial scar characterization with cardiac magnetic resonance imaging (CMR) may predict the occurrence of ventricular tachyarrhythmia and appropriate ICD therapy in patients with an ischemic cardiomyopathy (ICMP). Methods: In 100 patients with an ICMP, CMR was performed prior to ICD implantation. We assessed clinical variables and multiple CMR scar characteristics (infarct core mass, peri-infarction mass, ratio of scar to left ventricular mass and the ratio of peri-infarct to total infarction mass). The primary end-point was sustained ventricular tachycardia and/or appropriate ICD therapy (ATP and shock). The secondary end-point was all-cause death. Results: Mean follow-up was 5.2±1.1years. There were 35 patients with appropriate ICD therapy (16 ICD shocks) and 27 deaths. Mean peri-infarction mass and the ratio of peri-infarction to core-infarction mass were significantly higher in patients with the primary endpoint (both p-values 0.03). CMR scar indices were not significantly different for the secondary endpoint. In multivariate analysis with correction for age, gender, NYHA-class, LVEF, ratio of peri-infarction to core infarction mass, ratio of infarction mass to left ventricular mass, and peri-infarction to total infarction mass ratio, the latter two indices were independently and significantly associated with the time to primary endpoint (LR 4.1, p=0.04 and LR 15.0, p=0.0001 respectively). CMR scar indices were not significantly associated with time to death. Conclusion: Higher ratio of peri-infarction to total infarction mass, and higher relative infarction mass may both indicate higher vulnerability for ventricular tachyarrhythmia. Thus, CMR scar characterization could be useful in risk stratification in patients with ICMP.