Relationship Between Exercise-Induced Myocardial Ischemia and Reduced Left Ventricular Distensibility in Patients with Nonobstructive Hypertrophic Cardiomyopathy

Many studies have demonstrated that reduced left ventricular (LV) diastolic distensibility plays a key role in the pathophysiology of hypertrophic cardiomyopathy (HCM). However, the relationship between myocardial ischemia and reduced LV distensibility in HCM remains unclear. We aimed to clarify the relationship between exercise-induced ischemia and reduced LV distensibility in patients with HCM. Twenty patients with HCM and 5 age-matched control subjects underwent stress-redistribution (201)Tl myocardial scintigraphy and biventricular cardiac catheterization and echocardiography at rest and during exercise. Scintigraphic defect analysis was interpreted using Berman's 20-segment model. The summed stress score (SSS) was calculated as the sum of scores of the 20 LV segments and the summed difference score (SDS) was calculated as the sum of differences between each of the 20 LV segments on stress and rest images. Patients were divided into 2 groups according to the (201)Tl defect as follows: 9 patients with an SSS on (201)Tl of >or=10 and an SDS on (201)Tl of >or=5 (ischemic group) and 11 patients with an SSS of