Usefulness of Achieving ≥10 METs With a Negative Stress Electrocardiogram to Screen for High-Risk Obstructive Coronary Artery Disease in Patients Referred for Coronary Angiography After Exercise Stress Testing

Abstract

Functional capacity in exercise stress testing is an independent predictor of cardiac events. Routine use of nuclear perfusion imaging increases radiation burden and cost. Our goal was to assess the clinical utility of exercise functional capacity with stress electrocardiogram (ECG) as an adjunct in predicting the presence of high-risk obstructive coronary artery disease (CAD) on diagnostic coronary angiography. We performed a retrospective study of patients who underwent exercise stress testing for the evaluation of chest pain and underwent diagnostic coronary angiography within the subsequent 3 months. High-risk CAD was defined as coronary artery diameter stenosis of ≥70% in the proximal left anterior descending artery, ≥70% diameter stenosis in 3 major epicardial arteries, or ≥50% diameter stenosis in the left main artery. Univariable and multivariable analyses were performed to identify predictors of high-risk CAD. Of the 412 patients, 105 (25%) had high-risk CAD on coronary angiography. On multivariate logistic regression, we found that positive stress ECG, abnormal stress imaging, left ventricular ejection fraction, and male gender were independent predictors of high-risk CAD. The strongest predictor was positive stress ECG (hazard ratio 3.16, 95% confidence interval 1.90 to 5.27, p <0.001). Functional capacity measures alone were not independent predictors of high-risk CAD. Achieving ≥10 METs with a negative stress ECG resulted in 94% sensitivity and 97% negative predictive value in identifying high-risk CAD. This supports the strategy for provisional use of myocardial perfusion imaging in patients with low functional capacity and/or abnormal stress ECG to minimize cost and radiation exposure.