Background: Essential hypertensive patients (EH) are characterized by increased arterial stiffness. The renin-angiotensin system (RAS) activation is an important pathophysiological mechanism for arterial stiffening. Aliskiren is a novel direct renin inhibitor, whose effects on arterial elastic properties in EH are unknown. In this study we evaluated whether aliskiren, as compared to the ACE-inhibitor ramipril, can improve arterial stiffness and peripheral wave reflection in untreated mild-moderate EH, according to a double-blind parallel-group study.

Methods: 40 EH were randomized to a 12-week treatment with aliskiren (300 mg/daily) or ramipril (10 mg/daily) (n=20 each group). At baseline and after treatment arterial stiffness was assessed as carotid-to-femoral pulse wave velocity (PWV) by arterial tonometry (Sphygmocor). Central blood pressure and augmentation index (AIx) was also assessed.

Results: Blood pressure values were similarly normalized by aliskiren (from 147±8/95±2 to 131±9/85±4 mmHg) and ramipril (from 149±6/96±6 to 133±8/86±3 mmHg). Central pulse pressure was also similarly decreased (aliskiren from 39.5±7.7 to 35.5±6.9 mmHg, P<0.01; ramipril from 38.4±8.9 to 34.8±5.7 mmHg, P<0.01). Aortic PWV was similarly decreased by aliskiren (from 7.7±1.2 to 7.1±1.3 m/s, P<0.05) and ramipril (from 7.5±1.1 to 6.9±1.1m/s, P<0.05). AIx was reduced after aliskiren (from 18.0±8.1 to 13.6±17.4%, P<0.05) and after ramipril treatment (from 19.1±8.3 to 17.1±8.1%, P<0.05), but aliskiren induced a significantly greater reduction (p<0.05).

Conclusions: These results indicate that RAS blockade by aliskiren and ramipril can improve aortic stiffness in EH. The direct renin inhibitor seems to have an additional positive effect on wave reflection, possibly linked to a effect on the peripheral microcirculation.