Loading...
Current guidelines (NEJM JW Cardiol Nov 1 2002) still support exercise treadmill testing (ETT) as an initial test for evaluation of ischemia in patients who have normal baseline electrocardiograms (ECGs) and are able to exercise. To assess the efficacy of additional testing, investigators recorded downstream testing within 6 months of ETT in 3656 patients without known coronary artery disease who underwent ETT at a large U.S. medical center. Tests were performed mostly for chest pain (61%) and various other symptoms (33%) but occasionally for asymptomatic patients (6%). ETT was positive in 4%, inconclusive in 29%, and negative in 68% of patients.
Within 6 months of ETT, 9.1% of patients were referred to noninvasive imaging, and 2.3% were referred to invasive angiography. During mean follow-up of 2.5 years, annual incidence of a combined endpoint (cardiovascular-related death, myocardial infarction, and coronary revascularization) was 12.4%, 1.3%, and 0.2% in those with positive, inconclusive, and negative ETT results, respectively. Rapid resolution of ECG changes during exercise was associated significantly with negative downstream tests and excellent prognoses, whereas typical angina despite negative ECG findings was associated significantly with positive downstream tests and poorer prognoses. Younger age, female sex, and achieving a higher level of exercise were associated significantly with negative downstream tests.
Christman MP et al. The yield of downstream tests after ETT: A prospective cohort study. J Am Coll Cardiol 2014 Feb 5; [e-pub ahead of print]. (http://dx.doi.org/10.1016/j.jacc.2013.11.052)
Sinusas AJ and Spatz ES.Reframing the interpretation and application of exercise electrocardiography. J Am Coll Cardiol 2014 Feb 5; [e-pub ahead of print]. http://dx.doi.org/10.1016/j.jacc.2013.12.026
Comment
These data confirm that exercise treadmill testing can help stratify risk for adverse cardiac events in patients without known coronary artery disease, although the combined endpoint included coronary revascularization, which might be a result of abnormal test results. Only limited conclusions can be drawn because of the study's single-center design and our inability to determine whether downstream testing was appropriate. Nonetheless, we should remember that rapidly resolving ECG changes are associated with a higher proportion of negative downstream tests and that typical angina on the treadmill is a cause for concern, even if ECG does not confirm inducible ischemia.