Use of risk stratification to identify patients with unstable angina likeliest to benefit from an invasive versus conservative management strategy

OBJECTIVES: This study was designed to determine whether patient characteristics collected at presentation can identify which patients benefit from immediate coronary angiography and revascularization. BACKGROUND: Risk stratification may offer a method for identifying which patients with unstable angina or non-Q-wave myocardial infarction (NQMI) are likeliest to benefit from invasive management strategies. METHODS: The analysis was based on data from a randomized controlled trial that enrolled 1,473 patients presenting with unstable angina or NQMI who were randomly assigned to an early invasive or early conservative (medical) management strategy. We constructed a risk-stratification score for each patient based on adjusted odds ratios for clinical variables likely to predict adverse outcomes. We stratified all trial subjects by their risk scores and studied the rates of death or myocardial infarction (MI) of the early invasive management strategy in each stratum. RESULTS: The final multivariate model included older age, ST segment depression on presentation, history of complicated angina before presentation, and elevation in baseline creatine kinase-MB fraction. Although patients with a higher risk score had an increased rate of death or MI within 42 days and 365 days (p < 0.001) in both management strategies, early invasive management for patients in the high and very high risk categories was associated with a lower rate of death or MI within 42 days compared with conservative management. No such benefit was seen in patients in the larger group of patients in the very low, low or moderate risk categories (p = 0.03 for the interaction between risk category and management assignment). CONCLUSIONS: Risk stratification may be an effective method for identifying those patients with unstable angina or NQMI most likely to benefit from early invasive management. Selective use of early invasive management can have a substantial impact in reducing morbidity and mortality in higher risk patients, but may not be warranted in lower risk patients.