Augmentation of myocardial blood flow in hypertensive heart disease by angiotensin antagonists: A comparison of lisinopril and losartan

Objectives The goal of this study was to compare myocardial perfusion reserve (MPR) before and after long-term treatment with lisinopril and losartan in patients with hypertension and left ventricular hypertrophy (LVH). Background Studies have suggested that treatment with angiotensin-converting enzyme inhibitors (ACEIs) improves MPR in patients with hypertension by potentiating endogenous bradykinins. Because angiotensin receptor blockers (ARBs) lack a direct effect on bradykinins, we hypothesized that they may not improve MPR. Methods We measured pre- and post-treatment myocardial blood flow (MBF) by positron emission tomography in 17 patients (lisinopril: 9 patients, losartan: 8 patients) with hypertension and LVH at baseline and after coronary vasodilation with intravenous dipyridamole. In addition, we measured rest and hyperemic blood flow in eight normotensive controls. Results Post-treatment maximal coronary blood flow and MPR in the lisinopril group increased significantly compared with pretreatment values (3.5 ± 1.2 vs. 2.6 ± 1.1 ml/min/g, P = 0.02; 3.7 ± 1.1 vs. 2.4 ± 1 ml/min/g, respectively, P = 0.002, respectively). Post-treatment hyperemic flow in the patients treated with lisinopril was not significantly different from corresponding measurements in controls (3.5 ± 1.2 vs. 3.9 ± 1 ml/min/g, respectively, P = NS). In the patients treated with losartan, there was no difference between pre- and post-treatment MBF values and MPR. Conclusions Myocardial perfusion reserve and maximal coronary flow improved in asymptomatic patients with hypertension-induced LVH after long-term treatment with lisinopril but not with losartan. Thus, ACEIs, but not ARBs, might be effective in repairing the coronary microangiopathy associated with hypertension-induced LVH.