Abstract 13420: Correlates of Myocardial Fibrosis in Hypertrophic Cardiomyopathy.

Introduction: The Hypertrophic Cardiomyopathy Registry (HCMR) is a NHLBI-funded study of 2764 HCM patients recruited from 44 sites worldwide. Baseline clinical evaluation included echo, cardiac magnetic resonance imaging (CMR), and blood drawn for genetic and biomarker analysis. Follow-up is 1.5 years to date. CMR protocol included short axis cines, pre-and post-contrast T1 mapping, and late gadolinium enhancement (LGE). Hypothesis: We hypothesized that demographic factors may relate to extent of LGE (replacement fibrosis) and T1 mapping (interstitial fibrosis). Methods: LGE assessed visually was categorized as none, >0-5, >5-10, >10-15 and >15% of LV mass. LGE relationship to continuous demographic variables was assessed by one-way analysis of variance. The relationship of native T1 (by field strength) and extracellular volume (ECV) with baseline variables were assessed by Pearson correlations, unpaired t-tests, or analysis of variance. Results: Of 2764 patients, 2556 (92%) had valid LGE values and 50% had any LGE. (Table) Only 2% of patients had LGE >15% of LV mass. Age was similar across LGE categories, but BMI declined with greater LGE extent. There were smaller % of whites and blacks with >15% LGE, but a larger % of other races (primarily Asian). With more LGE, a family history of HCM was more likely and hypertension less likely. The greater the LGE extent, the lower the LVEF. 2122 patients (77%) had valid native T1 and 1988 (72%) valid ECV measures. There was no relationship between age, BMI, or race with either T1 or ECV. Females had longer native T1 at 1.5T (p < 0.001), but not at 3T (p = 0.168). Females had higher ECV values (0.32±0.06 vs. 0.30±0.06, p<0.001). Conclusions: Baseline data from HCMR demonstrate that 2% of patients have LGE >15% of LV mass. These patients have more family history of HCM, are less often black or white, have less hypertension, lower BMI, and lower LVEF. These data suggest that extensive LGE, a risk factor for sudden cardiac death, may be more typical of familial, rather than sporadic or secondary disease. Ongoing genetic analysis may shed additional light. Interstitial fibrosis is greater in females with HCM. Longer follow-up is needed to demonstrate whether these baseline findings are associated with adverse cardiovascular outcome. [ABSTRACT FROM AUTHOR]