Superiority of Exercise Myocardial Perfusion Imaging Compared with the Exercise ECG in the Diagnosis of Coronary Artery Disease

Background: Wide variations in the sensitivity and specificity of the exercise ECG for the diagnosis of coronary artery disease (CAD) have been reported. The aim of this study was to reexamine the sensitivity and specificity of the stress ECG and stress myocardial perfusion imaging (MPI) relative to cardiac catheterization in an era of aggressive screening.

Methods And Results: We evaluated 218 patients [mean age: 62+/-13 (SD) years; 69% males] with symptoms of chest pain or dyspnea, normal resting ECGs, and no earlier myocardial infarction. All patients exercised to age-corrected and sex-corrected Bruce protocol times and achieved >or=85% of predicted maximum heart rate. Coronary angiography was performed within 3 months of stress testing. Sixty-six percent of patients had significant CAD by angiography. The overall sensitivity of the exercise ECG (36%) was significantly lower than that of exercise MPI (81%) (P<0.001). In addition, the specificity of the exercise ECG was higher in men than in women (94% men, 74% women; P<0.01), whereas there were no significant differences in sensitivity or specificity (79%) of MPI between men and women. In patients with multivessel CAD or proximal left anterior descending stenosis >or=70%, the sensitivity of the exercise ECG was higher (58%), but still less than MPI (88%) (P<0.01).

Conclusion: MPI is vastly superior to the stress ECG for the diagnosis of CAD, especially in patients with single-vessel CAD. Older literature reporting higher sensitivity for the stress ECG was likely biased by patients with more severe CAD and must be reexamined in the era of earlier diagnosis and intervention.