Prospective comparison of unstable angina versus non-Q wave myocardial infarction during antithrombotic therapy. Antithrombotic Therapy in Acute Coronary Syndromes Research Group.

OBJECTIVES

This study was designed to compare the response of unstable angina and non-Q wave myocardial infarction during treatment with antithrombotic therapy.

BACKGROUND

Antithrombotic therapy is beneficial in patients with these two coronary syndromes.

METHODS

In a multicenter trial of antithrombotic therapy in unstable angina or non-Q wave myocardial infarction, 358 patients admitted within 48 h of chest pain were randomized to antithrombotic therapy with either 1) aspirin alone, or 2) aspirin plus heparin followed by aspirin plus warfarin, and were prospectively followed up for 12 weeks. Admission cardiac enzyme analyses revealed unstable angina in 268 patients and non-Q wave myocardial infarction in 62. Given an event rate of about 25%, this study has a power of 80% to detect a 50% difference between the two groups.

RESULTS

Patients with unstable angina and non-Q wave myocardial infarction were similar with regard to age, gender, coronary risk factors and prior antianginal medication. Primary end points at 12 weeks were recurrent ischemia, infarction and death. [table: see text] In the non-Q wave group, all infarctions and death occurred within the 1st week.

CONCLUSIONS

Patients with unstable angina or non-Q wave myocardial infarction on antithrombotic therapy have a similar total number of ischemic events by 12 weeks. However, despite maximal medical therapy with antianginal and antithrombotic medication, patients with non-Q wave infarction have a significantly higher rate of reinfarction and death.