Introduction:
Left ventricular non-compaction (LVNC) is characterized by extensively trabeculaed myocardium adjacent to normal compacted myocardium of the left ventricle (LV). Hypertrophic cardiomyopathy (HCM) typically appears as diffuse or segmental LV hypertrophy, with or without outflow tract obstruction. Cardiac sarcomere mutations are present in most HCM cases and have also been identified in LVNC. Whether or not there is clinically significant phenotypic overlap between the two diseases is less well understood. We present a case of known HCM that met criteria for both LVNC and HCM by cardiac MRI.
Case:
A 49-year old man with HCM due to a c.3742_3759dup variant in MYBPC3 presented to clinic after an episode of syncope and ICD firing. In clinic, the device was interrogated and he was found to have had ventricular flutter which was successfully treated with one shock and a new, high (>20%) burden of premature ventricular beats. An echocardiogram showed a stable ejection fraction at 42%, mild concentric LV hypertrophy without obstruction and a newly dilated LV with an end diastolic diameter of 7.1cm (previously 6.2cm). A cardiac MRI was performed (
Figure
) and showed LV noncompaction and diffuse transmural and mid myocardial hyperenhancement/fibrosis of the septum, basilar lateral wall, anterior wall, and distal right ventricle consistent with patient's long-standing history of hypertrophic cardiomyopathy.
Discussion:
This case highlights the phenotypic overlap between HCM and LVNC by cardiac MRI. Had this patient not already carried a genetic diagnosis of HCM, he would likely have been diagnosed with LVNC based on this cardiac MRI. The phenotypic overlap in these diseases raises questions about ICD guidelines, the role of anticoagulation and prognosis.
Classical Cardiac MRI Findings in a Case of Hypertrophic Cardiomyopathy
