Olmesartan, but not amlodipine, improves endothelium-dependent coronary dilation in hypertensive patients.
OBJECTIVE
We aimed to compare the effects of the angiotensin II receptor blocker (ARB) olmesartan versus the calcium channel blocker (CCB) amlodipine on coronary endothelial dysfunction in patients with hypertension.


BACKGROUND
Angiotensin II receptor blockers are thought to have greater beneficial effects than CCBs on coronary vasomotion by directly blocking action of angiotensin II.


METHODS
Twenty-six patients with untreated essential hypertension were prospectively assigned to treatment with either olmesartan (27.7 +/- 12.4 mg/day, n = 13) or amlodipine (5.6 +/- 1.5 mg/day, n = 13) for 12 weeks. Changes of corrected myocardial blood flow (DeltaMBF) and coronary vascular resistance (DeltaCVR) from rest to cold pressor were measured by using 15O-water and positron emission tomography before and after treatment. Blood biomarkers including lipids, glucose, insulin, high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-alpha, and superoxide dismutase (SOD) were also measured.


RESULTS
Olmesartan and amlodipine reduced blood pressure (BP) to the same extent (-28.7 +/- 16.2 mm Hg vs. -26.7 +/- 10.8 mm Hg). In the olmesartan group, DeltaMBF tended to be greater (-0.15 +/- 0.19 ml/g/min vs. 0.03 +/- 0.17 ml/g/min, p = 0.09 by 2-way analysis of variance), and DeltaCVR was significantly decreased (7.9 +/- 23.5 mm Hg/[ml/g/min] vs. -16.6 +/- 18.0 mm Hg/[ml/g/min], p < 0.05) after treatment, whereas these parameters did not change in the amlodipine group (DeltaMBF: -0.15 +/- 0.12 ml/g/min vs. -0.12 +/- 0.20 ml/g/min; DeltaCVR: 6.5 +/- 18.2 mm Hg/[ml/g/min] vs. 4.8 +/- 23.4 mm Hg/[ml/g/min]). Serum SOD activity tended to increase (4.74 +/- 4.77 U/ml vs. 5.57 +/- 4.74 U/ml, p = 0.07 by 2-way analysis of variance) only in the olmesartan group.


CONCLUSIONS
Olmesartan, but not amlodipine, improved endothelium-dependent coronary dilation in hypertensive patients independent of BP reduction. These beneficial effects on coronary vasomotion might be via an antioxidant property of ARBs.
Naya
Masanao
M
Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Tsukamoto
Takahiro
T
Morita
Koichi
K
Katoh
Chietsugu
C
Furumoto
Tomoo
T
Fujii
Satoshi
S
Tamaki
Nagara
N
Tsutsui
Hiroyuki
H
D000328:Adult; D017311:Amlodipine / Q000008:administration & dosage*; D001774:Blood Chemical Analysis; D015331:Cohort Studies; D003326:Coronary Circulation / Q000187:drug effects*; D023921:Coronary Stenosis / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004452:Echocardiography; D004730:Endothelium, Vascular / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000188:drug therapy*; D007093:Imidazoles / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011336:Probability; D011446:Prospective Studies; D018570:Risk Assessment; D013777:Tetrazoles / Q000008:administration & dosage*; D016896:Treatment Outcome; D014664:Vasodilation / Q000187:drug effects
D007093:Imidazoles; D013777:Tetrazoles; D017311:Amlodipine; C437965:olmesartan