Imaging Phenotype Versus Genotype in Hypertrophic Cardiomyopathy

Abstract

H ypertrophic cardiomyopathy (HCM) is a common monogenetic cardiac disease with a prevalence of 0.2% 1 that usually is inherited as an autosomal dominant trait with variable penetrance and expression. Clinically, HCM is defined by the presence of left ventricular (LV) hypertrophy (LVH) unexplained by abnormal loading conditions. 1 The natural history varies from an asymptomatic course to drugrefractory angina/dyspnea, sudden cardiac death (SCD), and end-stage heart failure. The incidence of HCM-related SCD is approximately 1% to 2% in children and adolescents and 0.5% to 1% in adults. 2,3 In this review, we examine the impact of advanced diagnostic imaging technologies on HCM, with particular emphasis on the detection of particular genetic subtypes.

Geometric Assessment of Asymmetric Septal Hypertrophic Cardiomyopathy by CMR

“…Of 150 patients with HCM referred for CMR between January 2007 and December 2010, asymmetrical septal HCM was diagnosed in 137 patients (n ϭ 71 in Leuven, Belgium, and n ϭ 66 in Pisa, Italy), based on the presence of a septal wall thickness (WT) Ն15 mm and a septal to free wall WT ratio Ն1.3 in the absence of other disease that could justify the magnitude of hypertrophy (1,2). Left ventricular outflow tract (LVOT) obstruction was defined as a peak resting gradient Ն30 mm Hg on Doppler echocardiography (8). Another 5 patients were excluded because of "end-stage" HCM (n ϭ 4) and healed transmural anterior infarction (n ϭ 1).…”

Cardiac Magnetic Resonance in Hypertrophic Cardiomyopathy

“…Figure 2 highlights the areas where CMR potentially has incremental utility. Although a more comprehensive algorithm detailing the step-by-step diagnostic approach in HCM has been detailed elsewhere (17), a simplified approach to the differential diagnosis of HCM has been outlined in Figure 3. CMR enables the precise characterization of subtle disease phenotypic variations (Figs.…”

The Mitral Valve in Hypertrophic Cardiomyopathy

“…Recognition of abnormalities of the mitral leaflets or mitral apparatus has implications for the selection of the optimal treatment strategy for patients with obstructive HCM. 4,19 Over the past 50 years, we have had to revise our thinking about HCM on numerous occasions. 1 It is ironic that a disease that was first considered to be a mimicker of aortic stenosis may actually directly affect the mitral valve.…”