The study evaluated the effects of irbesartan on patients with heart failure and a preserved left ventricular ejection fraction (LVEF ≥ 45%). A total of 4128 patients aged 60 years or older, with New York Heart Association (NYHA) class II, III, or IV heart failure and an LVEF of at least 45%, were randomly assigned to receive either 300 mg of irbesartan or placebo daily. The primary composite outcome was death from any cause or hospitalization for cardiovascular causes. Secondary outcomes included death from heart failure, hospitalization for heart failure, and quality of life. During a mean follow-up of 49.5 months, the primary outcome occurred in 742 patients in the irbesartan group and 763 in the placebo group. The hazard ratio for the primary outcome was 0.95 (95% CI, 0.86 to 1.05; P = 0.35). There were no significant differences in other secondary outcomes, such as death from any cause, hospitalization for cardiovascular causes, or changes in the Minnesota Living with Heart Failure scale or NT-proBNP levels. The study concluded that irbesartan did not improve outcomes in patients with heart failure and a preserved LVEF, despite the involvement of the renin-angiotensin-aldosterone system in many of the associated processes.The study evaluated the effects of irbesartan on patients with heart failure and a preserved left ventricular ejection fraction (LVEF ≥ 45%). A total of 4128 patients aged 60 years or older, with New York Heart Association (NYHA) class II, III, or IV heart failure and an LVEF of at least 45%, were randomly assigned to receive either 300 mg of irbesartan or placebo daily. The primary composite outcome was death from any cause or hospitalization for cardiovascular causes. Secondary outcomes included death from heart failure, hospitalization for heart failure, and quality of life. During a mean follow-up of 49.5 months, the primary outcome occurred in 742 patients in the irbesartan group and 763 in the placebo group. The hazard ratio for the primary outcome was 0.95 (95% CI, 0.86 to 1.05; P = 0.35). There were no significant differences in other secondary outcomes, such as death from any cause, hospitalization for cardiovascular causes, or changes in the Minnesota Living with Heart Failure scale or NT-proBNP levels. The study concluded that irbesartan did not improve outcomes in patients with heart failure and a preserved LVEF, despite the involvement of the renin-angiotensin-aldosterone system in many of the associated processes.