Background—Left ventricular (LV) hypertrophy, a marker of cardiac end-organ damage, is associated with an increased risk of cardiovascular morbidity and mortality. Inhibitors of the renin-angiotensin-aldosterone system may reduce LV mass to a greater extent than other antihypertensive agents. We compared the effect of aliskiren, the first orally active direct renin inhibitor, the angiotensin-receptor blocker losartan, and their combination on the reduction of LV mass in hypertensive patients.

Methods and Results—We randomized 465 patients with hypertension, increased ventricular wall thickness, and body mass index >25 kg/m² to receive aliskiren 300 mg, losartan 100 mg, or their combination daily for 9 months. Patients were treated to standard blood pressure targets with add-on therapy, excluding other inhibitors of the renin-angiotensin-aldosterone system and -blockers. Patients underwent cardiovascular magnetic resonance imaging for assessment of LV mass at baseline and at study completion. The primary objective was to compare change in LV mass index from baseline to follow-up in the combination and losartan arms; the secondary objective was to determine whether aliskiren was noninferior to losartan in reducing LV mass index from baseline to follow-up. Systolic and diastolic blood pressures were reduced similarly in all treatment groups (6.5±14.9/3.8±10.1 mm Hg in the aliskiren group; 5.5±15.6/3.7±10.7 mm Hg in the losartan group; 6.6±16.6/4.6±10.5 mm Hg in the combination arm; P<0.0001 within groups, P=0.81 between groups). LV mass index was reduced significantly from baseline in all treatment groups (4.9-, 4.8-, and 5.8 g/m² reductions in the aliskiren, losartan, and combination arms, respectively; P<0.0001 for all treatment groups). The reduction in LV mass index in the combination group was not significantly different from that with losartan alone (P=0.52). Aliskiren was as effective as losartan in reducing LV mass index (P<0.0001 for noninferiority). Safety and tolerability were similar across all treatment groups.

Conclusions—Aliskiren was as effective as losartan in promoting LV mass regression. Reduction in LV mass with the combination of aliskiren plus losartan was not significantly different from that with losartan monotherapy, independent of blood pressure lowering. These findings suggest that aliskiren was as effective as an angiotensin receptor blocker in attenuating this measure of myocardial end-organ damage in hypertensive patients with LV hypertrophy.