Coronary flow reserve is a comprehensive indicator of cardiovascular risk factors in subjects with chest pain and normal coronary angiogram

Background: The aim of the present study was to analyze the parameters related to baseline coronary flow velocity (CFV) and coronary flow reserve (CFR) using Doppler transthoracic echocardiography (TTE), and to assess their associations with components of the Framingham risk score (FRS), which estimates 10-year risk of coronary heart disease, in subjects with chest pain and a normal coronary angiogram. Methods and Results: A total of 354 individuals (mean age: 55±11 years, M:F ratio=186:168) with angina or angina-like chest pain and a normal coronary arteriogram were enrolled. CFR, using TTE and adenosine or dipyridamole, was measured within 2 weeks after coronary angiogram. The clinical, electrocardiographic, echocar-diographic and laboratory parameters related to baseline CVF and CFR were analyzed, and CFR was compared with FRS. There was an inverse correlation between baseline CFV and CFR (r=-0.374, P<0.001). On multivariate analysis the fulfilling of left ventricular hypertrophy criteria on electrocardiography was an independent predictor of baseline CFV for the upper 75% quartile (23.2≥cm/s; odds ratio (OR)=2.840, 95% confidence interval (CI) = 1.155-6.983, P=0.023). On multivariate analysis hemoglobin A1c level was independently related to a CFR <2.0 (OR=2.195, 95%CI = 0.920-1.005, P=0.013). CFR had an inverse correlation with FRS (r=-0.222, P<0.001). On multiple regression analysis among the components of the FRS system (FRSS), independent factors related to a CFR <2.0 included age (OR=1.033, 95%CI=1.000-1.067, P=0.041), high-density lipoprotein-cholesterol level (OR=0.961, 95%CI=0.933-0.991, P=0.012) and smoking status (OR=2.461, 95%CI =1.078-5.618, P=0.033), respectively. Conclusions: CFR can be a comprehensive indicator of cardiovascular risk factors, including parameters of the FRSS, in subjects with chest pain and a normal coronary angiogram.