No reflow-like pattern in intramyocardial coronary artery suggests myocardial ischemia in patients with hypertrophic cardiomyopathy

Background and purposeTo evaluate intramyocardial coronary flow velocity pattern by transthoracic Doppler echocardiography and its clinical significance in patients with hypertrophic cardiomyopathy (HCM).Methods and resultsIn 48 patients with HCM who had angiographically normal coronary artery, coronary flow velocity in the left anterior descending coronary artery (LAD) and intramyocardial coronary artery (IMCA) derived from LAD were evaluated using transthoracic Doppler echocardiography. Two clearly different flow patterns in the IMCA were observed in patients with HCM. Twenty-seven HCM patients (group A) had slow deceleration slope in the IMCA flow (average diastolic deceleration time, 989 ± 338; range, 585–1680) and the remaining 21 patients (group B) had steep deceleration slope with diastolic deceleration time <300 ms, resulting in a no reflow-like pattern in the IMCA flow (average diastolic deceleration time, 166 ± 67; range, 55–280). There were no significant differences in the clinical characteristics and LAD flow velocity profiles between the two groups. The incidence of cardiovascular symptoms (chest pain or syncope) was significantly higher in group B than in group A (67% vs. 26%, p < 0.01). Additionally, exercise-induced ischemia as detected by thallium-201 scintigraphy was significantly more frequent in group B than in group A (6 of 9 (67%) vs. 0 of 9 (0%), p < 0.01).ConclusionsTwo different intramyocardial coronary flow velocity patterns are observed in patients with HCM using transthoracic Doppler echocardiography. No reflow-like pattern in the IMCA is strongly related to myocardial ischemia in the absence of epicardial coronary artery stenosis, suggesting that coronary microvascular dysfunction may be a causative mechanism.