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Background: The HCMR (Hypertrophic Cardiomyopathy Registry) is a National Heart, Lung, and Blood Institute-funded, prospective registry of 2,755 patients with hypertrophic cardiomyopathy (HCM) recruited from 44 sites in 6 countries.Objectives: The authors sought to improve risk prediction in HCM by incorporating cardiac magnetic resonance (CMR), genetic, and biomarker data.Methods: Demographic and echocardiographic data were collected. Patients underwent CMR including cine imaging, late gadolinium enhancement imaging (LGE) (replacement fibrosis), and T1 mapping for measurement of extracellular volume as a measure of interstitial fibrosis. Blood was drawn for the biomarkers N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (cTnT), and genetic analysis.Results: A total of 2,755 patients were studied. Mean age was 49 ± 11 years, 71% were male, and 17% non-white. Mean ESC (European Society of Cardiology) risk score was 2.48 ± 0.56. Eighteen percent had a resting left ventricular outflow tract (LVOT) gradient ≥30 mm Hg. Thirty-six percent had a sarcomere mutation identified, and 50% had any LGE. Sarcomere mutation-positive patients were more likely to have reverse septal curvature morphology, LGE, and no significant resting LVOT obstruction. Those that were sarcomere mutation negative were more likely to have isolated basal septal hypertrophy, less LGE, and more LVOT obstruction. Interstitial fibrosis was present in segments both with and without LGE. Serum NT-proBNP and cTnT levels correlated with increasing LGE and extracellular volume in a graded fashion.Conclusions: The HCMR population has characteristics of low-risk HCM. Ninety-three percent had no or only mild functional limitation. Baseline data separated patients broadly into 2 categories. One group was sarcomere mutation positive and more likely had reverse septal curvature morphology, more fibrosis, but less resting obstruction, whereas the other was sarcomere mutation negative and more likely had isolated basal septal hypertrophy with obstruction, but less fibrosis. Further follow-up will allow better understanding of these subgroups and development of an improved risk prediction model incorporating all these markers. [ABSTRACT FROM AUTHOR]

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]