Influence of severity of heart failure on the efficacy of angiotensin-converting enzyme inhibition.

Angiotensin-converting enzyme (ACE) inhibition slowed the progression of congestive heart failure (CHF) in 170 patients who were randomly assigned to either captopril or placebo in the Munich Mild Heart Failure Trial. The two major end points were progression from New York Heart Association (NYHA) functional classes I, II, or III to class IV, despite optimal, adjusted standard therapy, and death due to CHF. The relative risk for progressive CHF with captopril therapy was 0.34 (95% confidence interval = 0.17-0.68; p = 0.01). A total of 52 prerandomization variables were tested to determine their contribution to disease progression. Logistic regression analysis revealed 5 independent risk factors for progressive CHF: NYHA class, left ventricular end-systolic diameter, need for diuretic, age, and cardiothoracic ratio. The presence of greater than 2 of these risk factors increased the odds ratio for progression to 8.13 (p less than 0.001) compared with the presence of 0-2 risk factors. However, the effectiveness of captopril in preventing progression was higher within the subgroup of patients who had less severe CHF: the odds ratio was 0.12 (95% confidence interval = 0.03-0.45; p less than 0.01) for patients in NYHA class I or II on captopril and was 0.83 for those in class III. We conclude that the severity of CHF, as represented by the above-defined risk factors, is directly related to the likelihood for the development of progressive heart failure. However, the less severe the heart failure, the more effective the treatment with captopril will be in preventing disease progression. Thus, ACE inhibition has considerable potential for improving the prognosis of patients with mild heart failure.