To the Editor.
—Enalapril, an angiotensin converting-enzyme inhibitor, is known to be beneficial in the treatment of severe heart failure.1 Now, the Captopril-Digoxin Multicenter Research Group reports that another angiotensin converting-enzyme inhibitor, captopril, is better than digoxin, which, in turn, is no better than placebo in the treatment of patients in sinus rhythm with mild to moderate heart failure.2 Yet, the conclusions of the study depend on a precision that is lacking in the methods employed, principally, the treadmill exercise test and functional classification by the New York Heart Association.Dyspnea and fatigue are subjective end points of a treadmill exercise test that can be influenced not only by the patient but perhaps more importantly by the physician who is monitoring the test. The latter can shorten or lengthen the exercise time by whim or will, and the difference may exceed that of the advantage of 1½ minutes
Zatuchni J. Captopril and Digoxin in Mild to Moderate Heart Failure. JAMA. 1988;259(24):3557. doi:10.1001/jama.1988.03720240019013