Distinct Subgroups in Hypertrophic Cardiomyopathy: Baseline Results From HCMR

Background: The Hypertrophic Cardiomyopathy Registry (HCMR) is an NHLBI-funded, prospective registry of 2755 patients with HCM recruited from 44 sites in 6 countries. Objectives: HCMR was designed to improve risk prediction in HCM by incorporating cardiovascular 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 (ECV) as a measure of interstitial fibrosis. Blood was drawn for biomarker (N-terminal pro brain natriuretic peptide, NTproBNP and high sensitivity troponin T, cTnT) and genetic analysis. Results: A total of 2755 patients were studied. Mean age was 49±11 years, 71% were male, and 17% non-white. Mean ESC risk score was 2.48±0.56. Twenty four % had a resting left ventricular outflow tract (LVOT) gradient ≥ 30mmHg. Thirty six percent had a sarcomere mutation identified. Fifty percent had any LGE, which was more common and extensive in patients who were sarcomere mutation (+), had reverse septal curvature morphology and no significant resting LVOT obstruction. Those without LGE were more likely sarcomere mutation (-), had isolated basal septal hypertrophy, and more LVOT obstruction. Interstitial fibrosis was present in segments both with and without LGE. Serum NTproBNP and cTnT levels correlated with increasing LGE and ECV in a graded fashion. Conclusions: The HCMR population has characteristics of mild-to-moderate risk HCM. Baseline data separated patients broadly into 2 categories. One group was sarcomere mutation (+), more likely had reverse septal curvature morphology, more fibrosis, but less resting sarcomere mutation more likely had isolated basal septal obstruction but less fibrosis. Further follow-up will allow better understanding of these subgroups and development of an improved risk prediction model incorporating all of these markers. Abstract HCMR is a prospective registry of 2755 hypertrophic cardiomyopathy patients from 44 sites in 6 countries. Patients underwent cardiovascular magnetic resonance including cine imaging, late gadolinium enhancement imaging (LGE), and T1 mapping for measurement of extracellular volume and had blood drawn for biomarkers and genetics. Patients with sarcomere mutations more commonly had LGE and reverse septal curvature morphology but less resting outflow obstruction. Serum biomarkers correlated with the extent of LGE and ECV. Further follow-up will allow development of a useful risk prediction model incorporating these markers. biomarker and genetic variables that best predict risk of major adverse cardiac events in mild-to-moderate risk HCM.