Comparison of angiotensin-converting enzyme inhibitor alone and in combination with irbesartan for the treatment of heart failure.

Objective: Angiotensin-converting enzyme inhibitor (ACEI) is beneficial in patients with congestive heart failure (CHF). Some, but not all, angiotensin receptor blocker (ARB) was demonstrated to be effective as "add-on" therapy. We investigated whether irbesartan is useful as an add-on therapy in CHF.

Design: Randomized control trial.

Setting: Single center.

Patients: 50 CHF patients on stable doses of ACEI.

Interventions: Add-on therapy with irbesartan (300 mg/day) or continuation of conventional therapy (control group) for 1 year.

Main Outcome Measures: Serial clinical and echocardiographic assessment were performed as baseline, 3 months and 1 year after therapy.

Results: There was no difference in clinical characteristics between 2 groups. Patients in the add-on therapy group had significant increase in 6-Minute Hall-Walk distance (351+/-89 to 392+/-84 m, P<0.01), achieved higher METs exercise time on treadmill test (3.9+/-1.1 to 4.6+/-1.3 METs, P=0.01), reduction of NYHA Class (2.4+/-0.5 to 2.0+/-0.8, P<0.005) and improvement of QOL score (28+/-19 to 17+/-18, P<0.05). These parameters were not improved in the control group and a worsening of exercise capacity was observed (P<0.05). A reduction of left ventricular end-systolic diameter (4.94+/-0.85 vs 4.30+/-1.17 cm, P<0.05) was observed in the add-on group. At the end of 1 year, more patients have normal or abnormal relaxation pattern in the add-on group than the control group (82% vs 53% chi(2)=7.1, P=0.02). Blood pressure and renal function were unchanged in both groups.

Conclusion: The addition of irbesartan to conventional ACEI therapy in CHF further improves symptoms, exercise capacity and quality of life without adverse effects on hemodynamics and renal function.