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For people with stable chest pain and an intermediate pretest probability of obstructive coronary artery disease (CAD), an initial CT strategy fared similarly to invasive coronary angiography (ICA) for downstream cardiovascular outcomes, the DISCHARGE trial found.

Over a median follow-up of 3.5 years, 2.1% of patients randomized to CT experienced major adverse cardiovascular events, including cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke, versus 3.0% of those randomized to ICA (HR 0.70, 95% CI 0.46-1.07, P=0.10), reported Marc Dewey, MD, of Charité-Universitätsmedizin Berlin, and colleagues.

Initial CT was associated with the advantages of fewer major procedure-related complications (0.5% vs 1.9%, HR 0.26, 95% CI 0.13-0.55) and a reduction in coronary revascularization procedures (14.2% vs 18.0%, HR 0.76, 95% CI 0.65-0.90), the group noted in the .

There were no differences in angina relief or quality of life between the two groups.

ICA has long been considered the reference standard for the diagnosis of obstructive CAD. Yet over the past decade or so, coronary CT angiography has been gaining traction as the preferred imaging approach for the assessment of patients with chest pain, commented Joseph Loscalzo, MD, PhD, of Brigham and Women's Hospital and Harvard Medical School in Boston, .

CT's comparable effectiveness to ICA in DISCHARGE "is probably a consequence of the lack of effect of revascularization on cardiovascular events among most patients with stable angina and the limited number of those with high-risk anatomy who would benefit from revascularization in the trial," he suggested.

In the study, obstructive CAD was found in 25.7% of both the CT and ICA groups, and high-risk anatomy was noted in 13.9% versus 11.2%, respectively. The data suggest that this trial population had low risk of obstructive CAD rather than an intermediate risk, Loscalzo cautioned.

"The most recent guidelines of the American College of Cardiology-American Heart Association for the evaluation and diagnosis of chest pain recommend no testing and intensification of goal-directed medical therapy in low-risk patients," he noted.

DISCHARGE was conducted from 2015 to 2019 at 26 European centers and included patients with stable chest pain who had an intermediate (10%-60%) pretest probability of obstructive CAD and had been referred for ICA.

Patients in both groups were treated according to guidelines upon a finding of obstructive CAD. Decisions regarding treatment were made by local heart teams and referring physicians based on the imaging results.

The modified intention-to-treat analysis comprised 3,561 patients (mean age 60 years, 56.2% women). About 11% of patients in the CT group underwent percutaneous coronary intervention as initial management compared with 14.4% of those in the ICA group; usage of coronary artery bypass grafting occurred in 2.2% and 3.5%, respectively. Follow-up was completed for 98.9% of the study cohort.

However, the trial's open-label design was a major limitation, and the investigators left room for ascertainment bias. A 6% incidence of nondiagnostic CTs also suggested issues with the quality of imaging.

Loscalzo questioned the authors' choice of 10%-60% as the cutoff for intermediate risk and the inclusion of approximately 37% of patients with non-anginal chest pain. These factors may have contributed to the relatively low yield of patients with obstructive CAD in DISCHARGE, he said.

Going forward, he noted, there is more research needed on other noninvasive functional tests for CAD and whether coronary CT angiography-based measurement of plaque burden and lesion characterization improves predictive accuracy.

"No doubt, these and other questions will serve as the basis for future trials involving coronary CT angiography as its incorporation in the assessment of patients with stable angina continues to evolve," Loscalzo concluded.

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