Structural abnormalities in hypertrophic cardiomyopathy beyond left ventricular hypertrophy by multimodality imaging evaluation.

Background: Echocardiography- and cardiovascular magnetic resonance (CMR)-based studies have revealed a wide range of phenotypic manifestations in hypertrophic cardiomyopathy (HCM) apart from hypertrophy. This study sought to comprehensively describe a number of structural abnormalities in HCM beyond hypertrophy, by multimodality imaging.

Methods: A total of 100 HCM patients were prospectively enrolled, undergoing standard and contrast echocardiography, and CMR. Morphological characteristics involving mitral valve leaflets (MVL), subvalvular apparatus, and left ventricular cavity and wall were investigated. Seventy healthy volunteers served as control population.

Results: As assessed by echo, MVLs were longer in HCM patients than in controls (anterior method 1: 24[22,28] vs 19[18,20] mm, P < 0.01; anterior method 2: 27[24, 29] vs 21[19, 23] mm, P < 0.01; posterior: 15[12,19] vs 14[13,15] mm, P < 0.01). Abnormal chordal attachment to anterior MVL, anterior papillary muscle displacement, and accessory apical-basal muscle bundle were present in 42 (42%), 61 (61%), and 35 (35%) patients, respectively (P values vs controls <0.01); direct papillary muscle insertion into MVL and hypertrabeculation were found in two and five patients, respectively. Contrast echocardiography (n = 94) detected myocardial crypts in 15 patients (16%). Overall, 83% of HCM subjects had at least one of these phenotypic manifestations. Echocardiography and CMR agreement for MVL length was poor, while for structural characteristics was moderate to substantial (Cohen's Kappa: 0.53-1.00). Except for posterior MVL length and hypertrabeculation, the phenotypic characteristics studied had acceptable reproducibility by echocardiography and CMR.

Conclusions: Structural abnormalities in HCM beyond hypertrophy are significantly common. Multimodality imaging approach to these HCM facets by echocardiography and CMR is feasible and desirable.