AbstractBackgroundStatins improve endothelial functioning in patients with coronary artery disease and hypercholesterolemia, while substantially little is known about induced changes in myocardial microcirculation. However, although previous studies have suggested that microvascular abnormalities and endothelial dysfunction is responsible for slow coronary flow (SCF), there is no study investigating possible effects of statins on coronary microvascular function in patients with SCF.HypothesisWe prospectively investigated the effects of short‐term lipid‐lowering therapy with atorvastatin on coronary flow reserve (CFR) reflecting coronary microvascular function in patients with SCF assessed by transthoracic Doppler echocardiography (TTDE).MethodsIn an open clinical trial, CFR was studied in 20 subjects with SCF. TTDE was used to assess CFR at baseline as well as after 8 weeks of atorvastatin therapy. Coronary flow was quantified according to TIMI frame count (TFC). Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocities.ResultsCFR was independently correlated with TFC. After 8 weeks of atorvastatin therapy, CFR values increased significantly (1.95 ± 0.38 vs. 2.54 ± 0.56, (p < 0.001). No change in hemodynamic parameters was noted during the entire study. The improvement in CFR was not correlated to the amount of lipid‐lowering effect of atorvastatin.ConclusionsThese findings suggest that short‐term lipid‐lowering therapy with atorvastatin improved CFR, which reflects coronary microvascular functioning in patients with SCF. Copyright © 2007 Wiley Periodicals, Inc.