Recognizing heart attacks quickly is important. If given within a few hours of a heart attack, special “clot-buster” drugs (thrombolytics) and procedures with balloon catheters (angioplasty) can open up coronary arteries, reduce heart muscle damage, and save lives. Special decision aids may help doctors diagnose and treat heart attacks quickly. Some of the aids use formulas to estimate the chances of particular treatment outcomes based on each patient's age, sex, history, blood pressure, and ECG. Although they seem like a good idea, we do not know whether routine use of these aids changes the care that patients actually receive.