Aims Direct renin inhibitors provide an alternative approach to inhibiting the reninangiotensinaldosterone system (RAAS) at the most proximal, specific, and rate-limiting step. We tested the hypothesis that direct renin inhibition would attenuate left ventricular remodelling in patients following acute myocardial infarction receiving stable, individually optimized therapy, including another inhibitor of the RAAS. Methods and resultsWe randomly assigned 820 patients between ∼2 and 8 weeks following acute myocardial infarction, with the left ventricular ejection fraction (LVEF) ≤45%, and regional wall motion abnormalities (≥20% akinetic area), to receive aliskiren (n = 423), titrated to 300 mg, or matched placebo (n = 397), added to the standard therapy. All patients were required to be on a stable dose of an ACE-inhibitor or ARB, and beta-blocker unless contraindicated or not tolerated. Echocardiograms were obtained at baseline, and following 26-36 weeks of treatment. The primary endpoint was change in left ventricular end-systolic volume from baseline to 36 weeks, and was evaluable in 329 patients in the placebo group and 343 patients in the aliskiren group. We observed no difference in the primary endpoint of end-systolic volume change between patients randomized to aliskiren (-4.4 ± 16.8 mL) or placebo (-3.5 ± 16.3 mL), or in secondary measures of end-diastolic volume, or LVEF. We also observed no differences in a composite endpoint of cardiovascular death, hospitalization for heart failure, or reduction in LVEF >6 points. There were more investigator reported adverse events in the aliskiren group, including hypotension, increases in creatinine and hyperkalaemia. Conclusion Adding the direct renin inhibitor aliskiren to the standard therapy, including an inhibitor of the RAAS, in high-risk post-MI patients did not result in further attenuation of left ventricular remodelling, and was associated with more adverse effects. These findings do not suggest that dual RAAS blockade with aliskiren would provide additional benefit in these high-risk post-MI patients. © The Author 2011.