Comparison of the Use of Downstream Tests After Exercise Treadmill Testing by Cardiologists Versus Noncardiologists

Although exercise treadmill testing (ETT) is a useful initial test for patients with suspected cardiovascular (CV) disease, there is concern regarding the use of downstream imaging tests especially in the setting of equivocal or positive ETTs. Patients with no history of coronary artery disease who underwent ETT between 2009 and 2010 were prospectively included. Referring physicians were categorized as cardiologists and noncardiologists. Downstream tests included nuclear perfusion imaging, coronary computed tomography angiography, stress echocardiography, stress magnetic resonance, and invasive coronary angiography performed up to 6 months after the ETT. Patients were followed for CV death, myocardial infarction, and coronary revascularization for a median of 2.7 years. Among 3,656 patients, the ETT were negative in 2,876 (79%), positive in 132 (3.6%), and inconclusive in 643 (18%). Cardiologists ordered less downstream tests than noncardiologists (9.5% vs 12.2%, p = 0.02), with less noninvasive tests (5.9% vs 10.4%, p <0.0001) and more invasive angiography (3.6% vs 1.8%, p <0.0001). After adjustment for confounding, patients evaluated by cardiologists were less likely to undergo additional testing after equivocal (odds ratio: 0.65, p = 0.02) or positive ETT results (odds ratio: 0.39, p = 0.02), whereas after negative ETT, the odds ratio was 1.7 (p = 0.06). There was no difference in the rate of adverse CV events between patients referred by cardiologists versus noncardiologists. In conclusion, patients referred for ETT by cardiologists are less likely to undergo additional testing, particularly noninvasive tests, than those referred by noncardiologists. The lower rate of tests is driven by a lower rate of tests after positive or inconclusive ETT.