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

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% χ2 = 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.