Downstream imaging not necessary for all patients after treadmill testing

Among patients referred for further imaging after exercise treadmill testing, those who experienced rapid recovery of ECG changes during the test have the lowest subsequent diagnostic yield, according to recent results.

In a prospective cohort study, researchers evaluated 3,345 consecutive patients who underwent clinically recommended exercise treadmill testing at Brigham and Women’s Hospital from 2009 to 2010. No participants had known CAD or had previously experienced MI or undergone CABG or PCI. Tests were conducted according to established guidelines, using a symptom-limiting Bruce protocol. Results were classified as positive, negative or inconclusive according to standard benchmarks.

The researchers documented all noninvasive imaging and invasive angiography performed on each patient within 6 months of having undergone treadmill testing. The combined study endpoint was major adverse cardiac events, including CV death, MI and coronary revascularization, with a mean follow-up of 2.5 ± 1.1 years.

Across the cohort, 9.1% of participants received noninvasive imaging after treadmill testing, and 2.3% underwent invasive angiography. Diagnostic yield of downstream, noninvasive imaging varied from 0% to 21% across indications. In patients who experienced recovery of ECG changes within 60 seconds during treadmill testing, there was an association between negative downstream test results and excellent prognosis. Patients who experienced typical angina despite negative ECG results were more likely to have positive downstream test results and poor prognosis (P<.001). Other predictors of negative downstream tests included younger age (P<.001), female gender (P<.001), higher metabolic equivalents of task achieved during testing (P=.037) and rapid recovery of ECG changes (P=.013).

Patients achieved the combined endpoint in 2.2% of cases. CV-related death occurred in 0.25% of patients, whereas 0.3% had MI and 2% underwent revascularization. Survival free of CV-related death or MI was significantly lower among patients with inconclusive results from treadmill testing compared with those with negative results (P<.001).

The annual occurrence of the primary endpoint was 0.2%, 1.3% and 12.4% in patients with negative, inconclusive and positive treadmill testing results, respectively (P<.001). Patients who experienced rapid recovery of ECG changes had an annual incidence of 0.7% vs. 7.4% among patients with negative ECG and typical angina.

The researchers wrote that, in light of concerns regarding the overuse of CV imaging, these findings could aid in the identification of patients who might benefit from additional imaging after exercise treadmill testing. In an accompanying editorial, Albert J. Sinusas, MD, and Erica S. Spatz, MD, MHS, of Yale University School of Medicine, wrote that the findings identify important areas for improvement in diagnostic test selection.

“Questions around test performance and the appropriateness of downstream testing are increasingly relevant for the CV imaging community, particularly in light of the recent advances in noninvasive diagnostic testing modalities that have further expanded options for test selection,” Sinusas wrote. “It may be that interpreting physicians need to reconsider their role in informing Bayesian decision-making.”

For more information:

Christman MP. J Am Coll Cardiol. 2014;doi:10.1016/j.jacc.2013.11.052.

Sinusas AJ. J Am Coll Cardiol. 2014;doi:10.1016/j.jacc.2013.12.026.

Disclosure: The researchers report no relevant financial disclosures.