T1 measurements identify extracellular volume expansion in a genotyped hypertrophic cardiomyopathy population with and without left ventricular hypertrophy

Abstract

Background Myocardial fibrosis is a hallmark of hypertrophic cardiomyopathy (HCM) and may contribute to arrhythmias and heart failure. Sarcomere mutations appear to induce profibrotic changes before left ventricular hypertrophy (LVH) develops. Measuring T1 relaxation times with contrast cardiac magnetic resonance (CMR) allows robust quantification of the cardiac extracellular volume (ECV) and noninvasive assessment of diffuse myocardial fibrosis. Methods A genotyped HCM population underwent contrast CMR with measurement of T1. Subjects included sarcomere mutation carriers with LVH (G+/LVH+, n = 37) and without LVH (G+/LVH-, n = 30); HCM patients without mutations (sarcomere-negative HCM, n = 11); and mutation-negative healthy controls (n = 10). Concurrent echocardiography and serum biomarkers of collagen synthesis, hemodynamic stress, and myocardial injury were available in a subset. Results Late gadolinium enhancement (LGE) was present in >60% of overt HCM patients but absent from G+/LVHsubjects. Compared to controls, ECV was increased in patients with overt HCM, as well as G+/LVH- mutation