Oral Abstract Session
SCMR 22nd Annual Scientific Sessions
Background: The Hypertrophic Cardiomyopathy Registry (HCMR) is an NHLBI-funded study of 2762 HCM patients recruited from 44 sites worldwide. Baseline clinical evaluation included echo, CMR, and blood drawn for genetic and biomarker analysis. Follow-up is 2 years to date. CMR protocol included short axis cines, pre-and post-contrast T1 mapping, and LGE. We hypothesized that morphologic and demographic features may relate to extent of LGE and interstitial fibrosis.
Morphology was visually assessed by a core laboratory. LGE was assessed visually and was categorized as none, >0-5, >5-10, >10-15 and >15% of LV mass (Figure 1). T1 and ECV were measured from 3 slices according to SCMR standards. The association of morphology categories with demographic and clinical variables was assessed by contingency table analysis (chi-square) for categorical variables and one-way analysis of variance for continuous variables. Association of baseline demographic and clinical variables with presence of LGE was assessed with logistic regression. Multiple linear regression was used to assess the association of demographic and clinical variables with ECV.
1202 (46%) had isolated basal septal hypertrophy, 1062 (40%) reverse septal curvature, 224 (8%) apical, 36 (1%) concentric, 79 (3%) midcavity obstruction with apical aneurysm, 33 (1%) other. (Figure 2) 2556 of 2762 patients (92%) had valid LGE values and 50% had any LGE. Mean LGE was 3.7±5.2% of LV mass. Only 2% had LGE >15%. Patients with reverse septal curvature hypertrophy or apical aneurysm patterns more likely had any LGE. (Table 1) Demographic correlates of LGE are shown in Table 2. BMI declined with greater LGE extent. Blacks were less likely to have LGE. With more LGE, a family history of HCM was more likely and hypertension less likely. More LGE was associated with lower EF. 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 higher ECV values (0.32±0.06 vs. 0.30±0.06, p<0.001). Patients with higher ECV had smaller BMI, were more likely female, less likely black, more commonly had a family history of HCM, and had a lower EF.
Baseline data from HCMR demonstrate that 2% of patients have LGE >15% of LV mass. Patients with more fibrosis are more likely to have asymmetric septal hypertrophy or apical aneurysm. They have more family history of HCM, are less often black, have less hypertension, and lower BMI. Interstitial fibrosis is prevalent and associated with smaller BMI, female gender, non-black race, and family history of HCM. These data suggest that extensive LGE and interstitial fibrosis may be more typical of familial, rather than sporadic or secondary disease. Ongoing genetic and biomarker analysis may shed additional light. Longer follow-up is required to demonstrate whether these baseline findings are associated with adverse cardiovascular outcome.