Utility of cardiac magnetic resonance in assessing arrhythmic risk in patients with non ischemic cardiomyopathy undergoing biventricular pacing

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Non-ischemic cardiomyopathy (NICM) is a common heart muscle disorder, which is responsible for approximately one-third of heart failure and is associated with significant morbidity and mortality. Recent data suggested the lack of mortality reduction from adding a defibrillator to cardiac resynchronization therapy (CRT) in all patients with NICM. Myocardial fibrosis detected by cardiac magnetic resonance late gadolinium enhancement (CMR-LGE) can help risk stratify patients who would benefit from adding a defibrillator to CRT in this patient population. Purpose We aim at assessing the relationship between the presence of myocardial fibrosis detected by CMR-LGE and the rate of major arrhythmic events (MAE) that included sustained VT, appropriate CRT-D intervention, VF, and SCD in patients with NICM undergoing (CRT) and to compare all-cause mortality and heart failure improvement between patients who receiving CRT-P vs those who receiving CRT-D based on the presence of myocardial fibrosis. Methods All consecutive patients with NICM satisfying a guideline directed indication for CRT implantation were included in the study after excluding patients who refused to consent, patients with acute decompensated heart failure and those contraindicated for a CMR. Patients were divided into two groups according to presence of fibrosis in cardiac MRI into (CRT-D/LGE) group and CRT-P/No LGE group and followed along for one year. Results Sixty patients were enrolled. Sixteen patients (26.6%) developed MAE during the study duration. Seven patients had myocardial fibrosis (receiving CRT-D as per protocol), while only nine patients had no myocardial fibrosis (receiving CRT-P as per protocol), (41.2% vs 20.9%, P=0.045). Presence of CMR-LGE, regardless the extent and distribution, predicted MAE with odd ratio 2.6 (CI=1.78-8.9, P=0.04). The presence of ≥7.5 % of myocardial fibrosis by CMR was associated with 54 % sensitivity and 100% specificity for MAE in the study population (Figure 1). However, All-cause mortality was significantly higher in the (CRT-P/No LGE) group vs (CRT-D/LGE) group [15 (34.9%) vs 2 (11.8%), P=0.076]. Comparison between both groups regarding symptoms of heart failure, QoL and ejection fraction is shown in Table 1. Conclusion In patients with NICM candidates for biventricular pacing, the presence of LGE on CMR, irrespective of the extent or segmental pattern, is independently associated with a major arrhythmic event and is associated with worse heart failure outcome. However, the absence of LGE did not rule out MAE and implanting CRT-P based on lack of fibrosis may result in higher all-cause mortality.