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

Background Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. Purpose 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). Methods and results Seventy-six patients with no evidence of myocardial perfusion abnormality on SPECT undergoing transthoracic Doppler echocardiography were enrolled in this study. Patients were divided into three age groups: 17 patients aged <70 years (Group I), 38 patients aged 70–79 years (Group II), and 21 patients aged ≥80 years (Group III). Compared with Group I, CFR was significantly lower in Group II (P<0.01) and Group III (P<0.01). Multivariate analysis showed that female (P=0.03), cigarette smoking (P=0.004), hemoglobin level (P=0.001) and LV mass index (P=0.03) were determinants for resting coronary flow velocity. On the other hand, age (P=0.008), hemoglobin level (P<0.001) and LV mass index (P=0.04) were determinants for hyperemic coronary flow velocity. Age was only independent determinant for CFR (β=−0.48 P<0.001). Conclusions Our data suggested that aging impaired CFR in patients with no evidence of myocardial perfusion abnormality primarily due to the decrease in hyperemic coronary flow velocity. Comparison of coronary flow reserve amon Funding Acknowledgement Type of funding source: None

Increased symmetric dimethylarginine, but not asymmetric dimethylarginine, concentrations are associated with transient myocardial ischemia and predict outcome

Objective Asymmetric and symmetric dimethylarginines (ADMA and SDMA) are endothelial dysfunction markers. ADMA inhibits synthesis of nitric oxide. We aimed to analyze both markers in patients with coronary artery disease (CAD) who were referred for stress/rest myocardial perfusion scintigraphy (MPS). Methods All patients underwent a 2-day dipyridamole (DP) stress/rest protocol. Thereafter, patients with transient myocardial perfusion abnormality were followed up and their coronary blood flow was quantitatively assessed. Venous blood was taken before and after DP stress to measure markers. Results Baseline ADMA and SDMA concentrations were significantly higher in patients with CAD compared with healthy subjects. Pre- and post-stress SDMA concentrations were significantly higher in patients with transient myocardial perfusion abnormality compared with those with negative MPS results. However, ADMA and L-arginine concentrations were not significantly different between the two groups. None of the markers were significantly different between patients with angiographically proven low coronary flow and those with normal coronary flow. Pre-stress SDMA concentrations were an independent predictor of cardiovascular mortality during a 8-year follow-up. Conclusions Elevated serum SDMA concentrations may be helpful for selecting high-risk patients with CAD if there is any doubt in interpreting MPS. SDMA concentrations may also predict cardiovascular outcome.