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

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. [Figure: see text] [Figure: see text]