Assessment of effect of angiotensin II receptor antagonist losartan on aortic distensibility in patients with essential hypertension by echocardiography

The effects of angiotensin II receptor antagonist losartan on elastic properties of aorta in patients with mild to moderate essential hypertension were assessed. The ascending aortic distensibility in 26 patients (48±3 years) with mild to moderate essential hypertension before and after 12 weeks of treatment with losartan (50 mg/day) was evaluated by using two-dimensional echocardiography. M-mode measurements of aortic systolic (D5) and diastolic diameter (Dd) were taken at a level approximately 3 cm above the aortic valve. Simultaneously, cuff brachial artery systolic (SBP) and diastolic (DBP) pressures were measured. Aortic pressure-strain elastic modulus (Ep) was calculated as Dd×(SBP−DBP)/(Ds−Dd)×1333 and stiffness index beta (β) was defined as Dd×Ln (SBP/DBP)/(Ds−Dd). Blood pressure significantly decreased from 148±13/95±9 mmHg to 138±12/88±8 mmHg (systolic blood pressure,P=0.001; diastolic blood pressure,P=0.003). There was no significant difference in pulse pressure before and after treatment with losartan (53±10 mmHg vs 50±7 mmHg). The distensibility of ascending aorta increased significantly as showed by the significant decrease in pressure-strain elastic modulus from 4.42±5.79×106 dynes/cm2 to 1.99 ±1.49×106 dynes/cm2 (P=0.02) and stiffness index beta from 27.4±32.9 to 13.3±9.9 (P=0.02). Although there was a weak correlation between the percent changes in pressure-strain elastic modulus and stiffness index beta and that in diastolic blood pressure after losartan treatment (r=0. 40,P=0.04 andr=0.55,P=0.004, respectively), no correlation was found between the percent changes in pressure-strain elastic modulus and stiffness index beta and that in systolic blood pressure (r=0.04,P=0.8 andr=0.24,P=0.2, respectively). Our study demonstrated that angiotensin II receptor antagonist losartan has a beneficial effect on aortic distensibility in patients with mild to moderate essential hypertension and this effect is partly independent of blood pressure reduction.