Atypical echocardiographic phenotype of end-stage hypertrophic cardiomyopathy: a case series

We fully documented the diagnostic process of three hypertrophic cardiomyopathy (HCM) cases without typical asymmetric myocardial hypertrophy, including medical histories, imaging, and laboratory tests, ultimately confirming the diagnosis through genetic testing. Case 1 presented with segmental wall motion abnormalities with thrombosis, requiring differentiation from coronary atherosclerotic heart disease; case 2 presented with restrictive hemodynamic changes that could be confused with restrictive cardiomyopathy such as amyloidosis; case 3 occurred in a pediatric setting and showed diffuse and concentric hypertrophy similar to metabolic disorders. Various imaging examinations were employed for differential diagnosis, and whole-exome sequencing identified a pathogenic MYBPC3 mutation in case 1 and pathogenic MYH7 mutations in cases 2 and 3, including a de novo variant in case 3. We provided appropriate treatment and follow-up for each case. Case 1's left ventricular ejection fraction increased to 48%, and cases 2 and 3 have not experienced worsening heart failure or malignant arrhythmic events based on an optimized drug regimen. This case series confirms the diversity of echocardiographic phenotypes in end-stage HCM, underscoring the role of multimodal imaging and genetic testing in diagnosis and differential diagnosis.