<qa>  What is the effect of angiotensin converting enzyme inhibitors on heart failure?In recent years the usefulness of angiotensin converting enzyme inhibitors and vasodilators as well as beta-blockers has been realized in the treatment of heart failure. Multi-center studies clinical trials have shown some benefit of angiotensin converting enzyme inhibitors on the morbidity and mortality of heart failure subjects, and physicians are also prescribing angiotensin converting enzyme inhibitors for the initial treatment of subjects with left ventricular dysfunction. Some subjects do not respond to angiotensin converting enzyme inhibitors and intolerance to these compounds has also been observed. Despite the significant reduction in mortality observed in limited controlled studies, the 5-year mortality of subjects with congestive heart failure continues to be high, indicating that there is a significant therapeutic gap in the treatment of this disease. 