Abstract
BackgroundSarcomeric gene mutations cause hypertrophic cardiomyopathy (HCM). In gene mutation carriers without left ventricular (LV) hypertrophy (G + LVH-), subclinical imaging biomarkers are recognized as predictors of overt HCM, consisting of anterior mitral valve leaflet elongation, myocardial crypts, hyperdynamic LV ejection fraction, and abnormal apical trabeculation. Reverse curvature of the interventricular septum (into the LV) is characteristic of overt HCM. We aimed to assess LV septal convexity in subclinical HCM.MethodsCardiovascular magnetic resonance was performed on 36 G + LVH- individuals (31 ± 14 years, 33 % males) with a pathogenic sarcomere mutation, and 36 sex and age-matched healthy controls (33 ± 12 years, 33 % males). Septal convexity (SCx) was measured in the apical four chamber view perpendicular to a reference line connecting the mid-septal wall at tricuspid valve insertion level and the apical right ventricular insertion point.ResultsSeptal convexity was increased in G + LVH- compared to controls (maximal distance of endocardium to reference line: 5.0 ± 2.5 mm vs. 1.6 ± 2.4 mm, p ≤ 0.0001). Expected findings occurred in G + LVH- individuals: longer anterior mitral valve leaflet (23.5 ± 3.0 mm vs. 19.9 ± 3.1 mm, p ≤ 0.0001), higher relative wall thickness (0.31 ± 0.05 vs. 0.29 ± 0.04, p ≤ 0.05), higher LV ejection fraction (70.8 ± 4.3 % vs. 68.3 ± 4.4 %, p ≤ 0.05), and smaller LV end-systolic volume index (21.4 ± 4.4 ml/m2vs. 23.7 ± 5.8 ml/m2, p ≤ 0.05). Other morphologic measurements (LV angles, sphericity index, and eccentricity index) were not different between G + LVH- and controls.ConclusionsSeptal convexity is an additional previously undescribed feature of subclinical HCM.
Highlights
Sarcomeric gene mutations cause hypertrophic cardiomyopathy (HCM)
Patient characteristics The study population consisted of 36 G + LVH- individuals with complete DICOM short and long axis images from within the original Heart Hospital cohort
G + LVH- cases deriving from 30 unrelated families, were compared to 36 matched healthy volunteers (Table 1)
Summary
Sarcomeric gene mutations cause hypertrophic cardiomyopathy (HCM). Hypertrophic cardiomyopathy (HCM) is the most common inherited monogenetic cardiac disease [1]. 60 % of cases are known to be caused by the presence of inherited sarcomeric protein mutations. These mutations may have incomplete expression with a variable phenotype and age-related expression. The first degree relatives of individuals with HCM have approximately. LV morphology has been extensively and classically characterized by echocardiography using specific parameters and indexes (sphericity, eccentricity, relative wall thickness) [11], most of which could be readily applied to CMR [12]
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