Multiple myocardial crypts on modified long-axis view are a specific finding in pre-hypertrophic HCM mutation carriers.

Aims: Crypts can be found with cardiovascular magnetic resonance imaging (CMR) in hypertrophic cardiomyopathy (HCM) mutation carriers without hypertrophy (carriers) using a modified two-chamber view through the inferoseptum, but also in other patients and healthy individuals with standard long-axis views. Since it is currently unknown if carriers display a specific crypt morphology, we compared crypts in carriers with other cardiac pathologies (controls). Besides, we aimed to determine the optimal imaging plane for the detection of crypts by comparing modified two-chamber views with standard long-axis views. Finally, we evaluated the accuracy of crypts to identify carriers in HCM family screening.
Methods and Results: Standard CMR long-axis views with additional modified two-chamber views were prospectively performed in carriers (n= 43), consecutive CMR control patients (n= 252), and mutation-negative family members (n= 15). Crypts were found in 70% (30/43) of carriers and in 12% (31/252) of controls (P< 0.001). Crypts in carriers showed deeper penetrance into the myocardium compared with controls (74 ± 21% vs. 59 ± 22%, P< 0.01). Detection of two or more crypts had a sensitivity of 51% and specificity of 94% for carriership. Modified two-chamber views doubled the sensitivity to detect crypts compared with standard long-axis views. In family screening, ≥2 crypts had a 100% positive predictive value to identify carriers.
Conclusions: Multiple crypts in the absence of left ventricular hypertrophy are highly specific for HCM mutation carriership and warrant clinical follow-up. A modified two-chamber view has a superior sensitivity compared with standard long-axis views for crypt detection. CMR may be of additional value to identify carriers in family screening.