Fig. 2

Assessment of perfusion defects in hypertrophic cardiomyopathy (HCM). Perfusion defects were assessed at rest (left panel) and adenosine stress (right panel). Stress perfusion defects were typically widespread throughout the 3 coronary territories. The endocardium was affected more than the epicardium. For visual assessment, perfusion was assessed using the American Heart Association (AHA) 17 segment model (excluding the apex) and scored as 0—no defect, 1—inducible perfusion defect < 50% of wall thickness, 2- inducible perfusion defect > 50% of wall thickness. The sum difference score (SDS) was calculated as the sum of the stress perfusion score minus the sum of the rest perfusion score. In this example, the SDS was (8 + 12 + 4)-(0 + 0 + 0) = 24. Quantitative perfusion was performed in a subgroup of patients and the myocardial perfusion reserve index (MPRI) compared to the SDS for validation