CT ‘safe alternative’ to coronary angiography for CAD diagnosis
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In patients with stable chest pain and intermediate pretest probability of CAD, risk for major adverse CV events was similar after CT or invasive coronary angiography, with fewer procedure-related complications with an initial CT strategy.
Invasive coronary angiography (ICA) is the reference standard for detection of CAD; however, CT may effectively reduce the approximately 2 million negative ICAs in Europe, Marc Dewey, MD, Heisenberg Professor of Radiology at the German Research Foundation and vice chair of the department of radiology at Charité University Medicine in Berlin, and colleagues wrote in the study background.
“CT has proven to be a safe procedure for patients with stable chest pain and suspected CAD,” Dewey told Healio. “It can therefore be concluded that CT, which we carried out in a standardized and quality-assured manner in the DISCHARGE trial, should be offered more frequently in routine care if CAD is suspected.”
The findings were presented at the European Congress of Radiology and simultaneously published in The New England Journal of Medicine.
Assessing intermediate-risk patients
For the DISCHARGE trial, Dewey and colleagues conducted a randomized trial comparing CT with ICA as initial diagnostic imaging strategies for guiding the treatment of 3,561 adults with stable chest pain who had an intermediate pretest probability of obstructive CAD and were referred for ICA at one of 26 European centers (56% women). The primary outcome was major adverse CV events, defined as CV death, nonfatal MI or nonfatal stroke over 3.5 years. Key secondary outcomes were procedure-related complications and angina pectoris.
“The rationale behind choosing this trial population was that intermediate-risk patients have been found to benefit the most from cardiac imaging,” the researchers wrote. “We found that CT may be suitable for certain intermediate-risk patients with stable chest pain who are referred for ICA because they have a clinical constellation suggesting a high risk of cardiovascular events, abnormal or inconclusive results on functional testing, or persistent symptoms despite medical treatment.”
Major adverse CV events occurred in 2.1% of participants in the CT group and 3% of participants in the ICA group, for an HR of 0.7 (95% CI, 0.46-1.07; P = .1). Major procedure-related complications occurred in 0.5% of participants in the CT group and in 1.9% of participants in the ICA group, for an HR of 0.26 (95% CI, 0.13-0.55).
Angina during the final 4 weeks of follow-up occurred in 8.8% of patients in the CT group and 7.5% of patients in the ICA group, for an OR of 1.17 (95% CI, 0.92-1.48).
“The annual incidence of such events was lower than expected in the two groups, possibly due to improvements in the methods used to perform ICA and general improvements in cardiovascular care during the past few years,” the researchers wrote. “The CT strategy was associated with fewer major complications and revascularization procedures, and there were no substantial differences in the incidence of angina in the two groups at follow-up.”
Dewey said the researchers plan to further evaluate the method for estimating the clinical probability of CAD developed for the DISCHARGE trial to understand whether clinical pretest probability estimation can improve referral and indication for CT in routine clinical care.
“CT is a safe alternative to cardiac catheterization for patients with suspected CAD that will likely change clinical practice worldwide by replacing invasive testing with CT in patients with stable chest pain who can be expected to benefit,” Dewey told Healio.
Unanswered questions
In a related editorial in NEJM, Joseph Loscalzo, MD, PhD, Hersey Professor of the Theory and Practice of Medicine at Harvard Medical School, chairman of the department of medicine and physician-in-chief at Brigham and Women’s Hospital, wrote that the trial raises “several additional questions of interest,” including why a pretest probability of obstructive CAD of 10% to 60% was chosen as the cutoff for intermediate risk and on what basis the scoring system was chosen to calculate that probability.
“Would a different range cutoff or a different scoring system have led to a different trial outcome?” Loscalzo wrote. “Was the inclusion of a large number of patients with nonanginal chest pain (> 35%) justified, and would their exclusion have led to a different trial outcome? Do these two trial design features account for the fact that only approximately one-quarter of the patients in each group had obstructive CAD, which suggests that the overall trial population had a low risk of obstructive CAD rather than an intermediate risk? 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.”
Loscalzo wrote that such questions will serve as a basis for future trials involving coronary CT angiography as its incorporation in the assessment of patients with stable angina continues to evolve.
References:
- DISCHARGE Trial Group. N Engl J Med. 2022;doi:10.1056/NEJMoa2200963.
- Loscalzo J. N Engl J Med. 2022;doi:10.1056/NEJMe2201446.
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Dewey M, et al. Clinical Trials in Radiology. Presented at: European Congress of Radiology; March 2-6, 2022; Vienna (hybrid meeting).
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