The case for unstable angina pectoris as a primary end point in primary prevention studies

Abstract

Coronary artery disease (CAD) primary end point definitions used in previous prevention trials are reviewed, as well as trends over time for CAD mortality, incidence and hospital discharges to see if new primary end points should be considered. CAD mortality has shown a dramatic decline in the U.S. in the last 20 years, whereas the decrease in the incidence of acute myocardial infarction (AMI) is less consistent. The decline in CAD incidence and mortality has been attributed to changes in lifestyle and increased medical/surgical intervention. Hospital discharge rates for CAD have risen during the past decade. In addition, although the rate of discharge for AMI appears to have stabilized, the rates for angina, and more dramatically for unstable angina, have increased. Unstable angina made up 4% of CAD discharges in 1980, and increased to 25% of CAD discharges in 1989. Because of these trends, future trials that rely solely on AMI as a primary end point will not reflect the actual experience with CAD presentation in the U.S. Given the greater availability of methods to diagnose unstable angina more accurately, and because of its high risk pathology, it is concluded that unstable angina should receive serious consideration as a primary end point in future primary prevention trials.