Angiotensin-converting–enzyme (ACE) inhibitors improve outcomes in patients with left ventricular dysfunction or heart failure. The Prevention of Events with Angiotensin Converting Enzyme Inhibition (PEACE) Trial investigators studied the effect of the ACE inhibitor trandolapril in patients with stable coronary disease and normal or only slightly reduced left ventricular function, and no benefit was found. This trial appears to define the limits of efficacy of ACE inhibition in patients who are already receiving maximal contemporary therapy. Blockade of the renin–angiotensin system has been shown to prolong survival and reduce adverse outcomes in patients with systolic heart failure 1 – 3 or left ventricular systolic dysfunction. 4 – 9 Indeed, angiotensin-converting–enzyme (ACE) inhibitors have become a cornerstone in the treatment of these patients. 10 – 12 In addition, post hoc analyses of patients from the Studies of Left Ventricular Dysfunction (SOLVD) 13 and the Survival and Ventricular Enlargement (SAVE) trials, 5 , 14 both randomized studies that involved patients with moderate-to-severe left ventricular dysfunction, showed a reduction in the rate of acute myocardial infarction in patients who were treated with an ACE inhibitor. These observations raised . . .