Abstract 3097: Significance of Delayed Enhancement with Contrast Enhanced Cardiovascular Magnetic Resonance in Hypertrophic Cardiomyopathy

Background. Cardiovascular magnetic resonance (CMR) with delayed enhancement (DE) can provide in vivo assessment of myocardial fibrosis. DE is an independent predictor of cardiovascular morbidity and mortality in ischemic and non-ischemic dilated cardiomyopathy but its clinical significance in hypertrophic cardiomyopathy (HCM) remains unresolved. Methods and Results. Cine and CMR-DE were performed in 202 HCM patients (42±17 years; 71% male). DE was identified in 103 (51%) HCM patients, occupying 9±11% (range 0.2 to 51%) of LV myocardial volume, including 12% with DE > 25%. DE was present all 10 patients with ejection fraction (EF) ≤50% (i.e., end-stage phase), 9/10 (90%) with EF 51–59% and 84/182 (45%) with EF ≥ 60% (p<0.001). %DE was inversely related to EF (r= −0.4; p< 0.001), most extensive in patients with EF ≤50% (27% vs.9% for other patients, p<0.001) and an independent predictor of EF (r= −0.6; p<0.001). Of the 182 patients with normal EF ≥60%, 49 (27%) were both asymptomatic and had DE (7±7% of LV; 51% transmural), including 7 patients ≥60 years. %DE was unassociated with heart failure symptoms (p=0.1) and age (r = 0.05; p = 0.6). Conclusions. In a large HCM cohort, DE was common and occupied substantial areas of LV myocardium. Importantly, DE was a strong and independent predictor of evolution to “end-stage” with systolic dysfunction. However, extensive DE was also present in many patients without heart failure symptoms, suggesting that such HCM patients undergo vigilant clinical surveillance (including serial CMR) for prospective detection of changes in clinical course and LV remodeling.