Clinical consequences of angiotensin-converting enzyme inhibitor withdrawal in chronic heart failure: a double-blind, placebo-controlled study of quinapril. The Quinapril Heart Failure Trial Investigators

Cardiac Investigation Unit, University Hospital, London, Ontario, Canada.

OBJECTIVES. This study was performed to assess the efficacy, safety and clinical consequences of abrupt cessation of quinapril therapy in a placebo-controlled, randomized, double-blind withdrawal trial. BACKGROUND. Angiotensin-converting enzyme inhibitor therapy has assumed a pivotal role in the treatment of chronic heart failure. Quinapril hydrochloride, a nonsulfydryl angiotensin-converting enzyme inhibitor, has shown beneficial clinical effects in previous studies. METHODS. After > or = 10 weeks of single-blind quinapril therapy, 224 patients with New York Heart Association class II or III heart failure were randomized in double-blind fashion to continue quinapril (n = 114) or to receive placebo (n = 110) for 16 weeks. Changes in treadmill exercise time, New York Heart Association functional class, quality of life and symptoms of heart failure were assessed. RESULTS. Patients withdrawn to placebo had a significant deterioration in exercise tolerance (median change -16 s with placebo vs. +3 s with quinapril, p = 0.015). New York Heart Association functional class (p = 0.004) and quality of life were improved and signs and symptoms of congestive heart failure were lessened in those remaining on quinapril therapy compared with those receiving placebo. During double-blind treatment, 18 patients were withdrawn from the placebo group because of worsening heart failure compared with 5 patients withdrawn from quinapril treatment (p < 0.001). Rather than a precipitous deterioration of clinical status or early incidence of adverse events, withdrawal from quinapril was associated with steady worsening of heart failure, beginning 4 to 6 weeks after randomization to placebo. CONCLUSIONS. Quinapril is effective and safe for maintaining clinical stability in patients with moderate congestive heart failure. Withdrawal of quinapril from patients with heart failure results in a slow progressive decline in clinical status.

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