A Decision Aid for Recognizing and Treating Heart Attacks Quickly

What is the problem and what is known about it so far?

Heart attacks occur when blood flow through the arteries to the heart (coronary arteries) is blocked long enough to damage a portion of heart muscle. Heart attacks usually cause symptoms such as severe chest pain, nausea, shortness of breath, or a feeling of impending doom. Most people with heart attacks also have abnormal heart tracings (electrocardiograms [ECGs]) that suggest poor blood flow to the heart.

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.

Why did the researchers do this particular study?

To see whether a decision aid (the Thrombolytic Predictive Instrument) that helps doctors predict outcomes of thrombolytic therapy actually increases the use of clot-buster drugs, angioplasty, or both.

Who was studied?

1197 adults from 28 urban, suburban, and rural emergency rooms who had ECGs that suggested an acute heart attack.

How was the study done?

Patients were randomly assigned to receive either usual care or care guided by the decision aid. Doctors obtained ECGs for all patients. For those assigned to the decision aid, researchers entered the following information into a computerized ECG machine: age, sex, history of high blood pressure and diabetes, and when heart attack symptoms began. The computer printout of the ECG for these patients showed doctors the chances of death, stroke, and bleeding with and without thrombolytic therapy. The researchers then followed patients in both groups to see which ones got thrombolytic therapy, angioplasty, or both.

What did the researchers find?

About 60% of the patients in both groups got thrombolytic therapy. An additional 7% to 8% in both groups had angioplasty. The decision aid compared with usual care increased use of thrombolytic therapy in certain subgroups of patients, including women, those whose heart attack was on the bottom (inferior) part of the heart, and those who were seen in hospitals that did not have expert heart doctors available on site.

What were the limitations of the study?

The decision aid predicted outcomes of only one type of treatment (thrombolytic therapy). Many doctors use other treatments for acute heart attacks. The study was not large enough to test whether using the decision aid reduced deaths from heart attacks.

What are the implications of the study?

Providing patient-specific predictions of thrombolytic outcomes to doctors increases use of thrombolytic therapy only in certain types of patients.