Angiotensin receptor antagonist losartan improves endothelial function of epicardial coronary arteries in patients with essential hypertension.

BACKGROUND: Angiotensin II can impair endothelial function, which is mediated by the angiotensin II type 1 receptor subtype. HYPOTHESIS: The study sought to determine whether treatment with the angiotensin II type 1 receptor antagonist losartan would restore the normal dilation of the left main coronary artery (LMCA) by cold pressor test in patients with essential hypertension, as shown by echocardiography.
METHODS: The study population included 30 patients with mild to moderate essential hypertension and 30 matched healthy subjects. Measurements of the cold pressor test-induced and nitroglycerin-induced changes in LMCA diameter by echocardiography were performed at the end of the washout period and after 12 weeks of losartan administration.
RESULTS: The percent change in LMCA diameter induced by the cold pressor test in hypertensive patients (-3.5 +/- 8.8%) was significantly lower than that in control subjects (10.2 +/- 3.7%, p<0.0001). After losartan treatment, the percent change (13.9 +/- 8.4%) was significantly higher than that before losartan treatment (-3.5 +/- 8.8%, p < 0.0001), but not significandy different between the 17 hypertensive patients with satisfactory control of blood pressure (13.8 +/- 9.1%) and the 13 hypertensive patients without satisfactory control of blood pressure (14.0 +/- 7.7%, p = 0.9). Losartan treatment in patients with essential hypertension did not modify the percent change in LMCA diameter caused by sublingual administration of nitroglycerin (23.2 +/- 14.0% vs. 27.3 +/- 13.7%, p = 0.2).
CONCLUSIONS: This study demonstrates that treatment with losartan normalized response of the LMCA to the cold pressor test in patients with mild to moderate essential hypertension and that this effect is not dependent on the reduction of blood pressure.