KIE: The National Heart, Lung, and Blood Institute has taken the unusual step of prematurely ending one of its major clinical trials, the Beta-Blocker Heart Attack Trial (BHAT), on the advice of its Policy and Data Monitoring Board. BHAT was a randomized, double-blind, multicenter clinical trial of propranolol hydrochloride vs. placebo in patients enrolled shortly after an acute myocardial infarction. This preliminary report explains that the trial was curtailed after data indicated that the group of patients receiving the drug experienced 26% lower mortality than the control group.