Effect on coronary flow velocity reserve in patients with type 2 diabetes mellitus: Comparison between angiotensin-converting enzyme inhibitor and angiotensin II type 1 receptor antagonist

Background The effects of angiotensin antagonists on coronary circulation in type 2 diabetes are unclear. We aimed to assess whether 4 weeks of treatment with angiotensin-converting enzyme inhibitor or angiotensin II type 1 receptor antagonist improves coronary flow velocity reserve (CFVR) in patients with type 2 diabetes. Methods Twenty-four asymptomatic patients with type 2 diabetes were randomly assigned to temocapril (2 mg/d) or candesartan (8 mg/d). Coronary flow velocity reserve, calculated as the ratio of adenosine-induced hyperemic to basal coronary flow velocity, was measured with transthoracic Doppler echocardiography. Coronary flow velocity reserve measurement and venous blood sampling were performed before and after 4 weeks of treatment. We also obtained CFVR and venous blood data in the 8 healthy controls. Results Coronary flow velocity reserve was significantly lower in patients than controls (temocapril group 2.74 ± 0.28, candesartan group 2.65 ± 0.30, controls 3.53 ± 0.23, P < .0001 for both, respectively). Blood pressure was reduced in both diabetic groups (n = 12 each) similarly 4 weeks after treatment. There were no significant differences between the 2 groups in venous blood data before or after treatment. However, CFVR increased significantly in the temocapril group (2.74 ± 0.28 to 3.31 ± 0.36, P < .0001), but not in the candesartan group (2.65 ± 0.30 to 2.71 ± 0.43, P = ns). Conclusions Coronary flow velocity reserve in patients with type 2 diabetes improved after treatment with temocapril but not with candesartan, suggesting that angiotensin-converting enzyme inhibitor, but not angiotensin II type 1 receptor antagonist, might have beneficial effects on coronary microangiopathy associated with type 2 diabetes.