The Case for Myocardial Ischemia in Hypertrophic Cardiomyopathy

Recently, a number of studies using contemporary cardiovascular imaging modalities such as positron emission tomography (PET) and cardiovascular magnetic resonance (CMR) have led to an enhanced understanding of the role that myocardial ischemia and its sequelae fibrosis play on clinical outcome. In this regard, studies with PET have shown that HCM patients have impaired MBF after dipyridamole infusion and that this blunted MBF is a powerful independent predictor of cardiovascular mortality and adverse LV remodeling associated with LV systolic dysfunction. Stress CMR with late gadolinium enhancement (LGE) has also shown that MBF is reduced in relation to magnitude of wall thickness and in those LV segments occupied by LGE (i.e., fibrosis). These CMR observations show an association between ischemia, myocardial fibrosis, and LV remodeling, providing support that abnormal MBF caused by microvascular dysfunction is responsible for myocardial ischemia-mediated myocyte death, and ultimately replacement fibrosis.