Factors predicting coronary flow reserve impairment in patients evaluated for chest pain: an ultrasound study.

Objective: To evaluate the impact of multiple cardiovascular risk factors on coronary flow reserve (CFR) in a large patient population with acute chest pain referred for coronary angiography.

Methods: Three hundred and ninety-four consecutive patients (mean age 59 +/- 10 years) were enrolled in the study. Blood flow velocity was measured, using transthoracic echocardiography, in the middle-distal tract of the left anterior descending coronary artery (LAD) at rest and during infusion of high-dose dipyridamole in 6 min. CFR was calculated as the ratio of hyperaemic to basal peak diastolic flow velocity. All patients underwent coronary angiography within 48-72 h of CFR evaluation and a LAD stenosis was considered significant for lumen diameter narrowing > or =70%.

Results: Out of 394 patients, 11 patients (3%) were excluded because of inadequate quality of the spectral Doppler envelope. In the group of 269 patients with LAD stenosis <70%, CFR was significantly reduced in 64 patients with >2 risk factors compared to 205 patients with < or =2 risk factors (2.24 +/- 0.48 vs. 2.52 +/- 0.53, P < 0.005). On multiple logistic regression analysis, age, hypertension and diabetes mellitus were related to reduced CFR. In 114 patients with significant LAD disease, CFR was not reduced in patients with multiple cardiovascular risk factors. On multiple logistic regression analysis, the percentages of stenosis and diabetes mellitus were independent determinants of CFR.

Conclusions: In patients with acute chest pain, the occurrence of multiple cardiovascular risk factors adversely affected CFR in an additive manner, in absence of significant angiographic stenosis. Diabetes mellitus was a powerful coronary risk factor decreasing CFR both in patients with or without significant LAD disease.