Resting ST-segment depression predicts exercise-induced subendocardial ischemia in patients with hypertrophic cardiomyopathy

Background Patients with hypertrophic cardiomyopathy (HCM) sometimes display characteristic electrocardiographic (ECG) findings at rest and develop subendocardial ischemia during exercise in the absence of coronary lesions. However, their relationship has not yet been fully clarified. Methods Exercise Tc-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM. We quantified transient left ventricular cavity dilation (LVCD) on exercise scintigrams, a parameter of subendocardial ischemia, and correlated the results with the ECG findings at rest and during exercise. Results Transient LVCD occurred during exercise in 17 (35%) patients with HCM. Hemodynamic parameters during exercise did not differ between HCM patients with and without transient LVCD. Multiple logistic regression analysis showed that transient LVCD was significantly associated with ST-segment depression at rest (χ2 = 5.00, odds ratio = 5.70, 95% confidence intervals 1.24–26.18, P = 0.025) and a greater total number of leads with resting ST-segment depression (χ2 = 6.38, odds ratio = 1.60, 95% confidence intervals 1.12–2.42, P = 0.012). The degree of LVCD was correlated with the total number of leads with ST-segment depression at rest (P = 0.002); the optimal cutoff for the diagnosis of transient LVCD was 3 with a sensitivity of 65%, a specificity of 90%, and an accuracy of 81%. Conclusions In patients with HCM, ST-segment depression at rest was accompanied by exercise-induced subendocardial perfusion abnormality as detected by myocardial scintigraphy. ST-segment depression at rest suggests that the subendocardium is predisposed to exertional ischemia.