Effects of aging on coronary flow reserve in patients with no evidence of myocardial perfusion abnormality.

Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. We tested the hypothesis that aging had impacts on coronary flow velocities and CFR in patients with no evidence of myocardial perfusion abnormality on single photon emission computed tomography (SPECT). Seventy-six patients undergoing transthoracic Doppler echocardiography with no evidence of myocardial perfusion abnormality on SPECT were enrolled in this study. CFR was defined as the ratio of hyperemic to resting peak diastolic coronary flow velocity. Patients were divided into the three groups based on age: 17 patients aged less than 70 years (Group I), 38 patients aged 70-79 years (Group II), and 21 patients aged 80 years or more (Group III). Compared with Group I, CFR was significantly lower in Group II (p < 0.01) and Group III (p < 0.01). Multivariate linear regression analysis showed that female (β = - 0.26, p = 0.03), cigarette smoking (β = - 0.32, p = 0.004), hemoglobin level (β = - 0.40, p = 0.001) and LV mass index (β = 0.24, p = 0.03) were determinants for resting coronary flow velocity. On the other hand, age (β = -0.30, p = 0.008), hemoglobin level (β = -0.47, p < 0.001) and LV mass index (β = 0.24, p = 0.04) were determinants for hyperemic coronary flow velocity. Age was only determinant for CFR (β = -0.48, p < 0.001). Our data suggested that that aging had a decreased effect on hyperemic coronary flow velocity rather than resting coronary flow velocity, and was further associated with impaired CFR in patients with no evidence of myocardial perfusion abnormality.