Stress Hypoperfusion and Tissue Injury in Hypertrophic Cardiomyopathy: Spatial Characterization Using High-Resolution 3-Tesla Magnetic Resonance Imaging

Background —Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy (HCM). Cardiovascular magnetic resonance (CMR) imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with HCM. Methods and Results —One hundred consecutive patients with HCM underwent CMR imaging. Cine, stress perfusion (SP), late gadolinium enhancement (LGE) and T2-weighted imaging techniques were employed. Each was spatially co-registered according to pre-defined segmental and sub-segmental models and blindly analyzed for abnormalities using validated techniques. Spatial associations between SP, LGE and T2 imaging were made at segmental and sub-segmental levels. Of the 100 patients studied the phenotype was septal in 86 and apical in 14. LGE imaging was abnormal in 79 (79%). Eighty-six patients met pre-specified safety criteria to undergo SP and ischemia was identified in 46 (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segments with hypertrophy. Sub-segmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from LGE and T2 abnormalities, typically seen in mid-wall and sub-epicardial zones. Conclusions —Inducible hypoperfusion is a common finding in HCM and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena appears distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.