(P132) PATIENTS WITH NON-ISCHEMIC CARDIOMYOPATHY AND MID-WALL STRIAE HAVE SIMILAR OUTCOMES AS PATIENTS WITH ISCHEMIC CARDIOMYOPATHY: A PROPENSITY-MATCHED ANALYSIS

Background: Device therapy recommendations in heart failure (HF) rely on left ventricular ejection fraction (LVEF) and presence of ischemic cardiomyopathy (ICM) for identifying appropriate candidates. Cardiac magnetic resonance (CMR) has evolved as an important modality for evaluating non-ischemic cardiomyopathy (NICM) using late gadolinium enhancement (LGE) to detect myocardial fibrosis. Mid-wall striae (MWS) fibrosis involving the basal septum is a specific LGE pattern detected in up to 1/3 of patients with dilated cardiomyopathy (DCM), which is associated with all-cause mortality, arrhythmic death, and HF hospitalizations. Our aim was to compare outcomes in those with NICM versus ICM with respect to the presence or absence of MWS fibrosis.

METHODS AND RESULTS: A total of 2,145 patients undergoing CMR for ICM or idiopathic NICM were identified. Patients with CMR-defined LV dysfunction (LVEF < 56%) and LGE-confirmed myocardial infarction were classified as ICM. NICM were required to have LV dysfunction and no history of obstructive CAD or any identifiable cause of cardiomyopathy. Presence of MWS was adjudicated by experienced readers, without knowledge of clinical history or outcomes. The primary outcome was a combination of ICD/CRT-D implantation, hospitalization for ventricular tachycardia, resuscitated cardiac death, or cardiovascular death. Associations with the primary outcome were assessed using univariable and multivariable Cox regression models, stratified by ICM versus NICM. Baseline data (table 1) reveal median age of 60 years and over 3/4 of patients were male. The MWS pattern was more common in NICM (72.3% of DCM) and lower LVEF (61.9% with LVEF < 35%). During a median follow-up period of 3.5 years, 170 patients experienced the primary endpoint. Patients with NICM with MWS were more likely to experience the primary endpoint compared to patients with NICM without MWS (16.9% vs. 10.6%, p=0.008). MWS was significantly associated with the combined outcome (unadjusted HR 1.74, 95% CI 1.31 – 2.32). Kaplan-Meier survival curves for the primary endpoint, stratified by diagnosis and MWS, are shown in figure 1. We identified a cohort of patients with ICM, without MWS, comparable to patients with NICM with MWS using 1:1 nearest neighbour propensity matching. There was no difference in the primary endpoint between these groups (figure 1, B).

Conclusion: Patients with MWS on CMR have poorer cardiovascular outcomes compared to patients without MWS irrespective of ischemic and non-ischemic etiology. Patients with NICM and MWS have a similar cardiovascular outcome when compared to patients with ICM and no MWS present.