CT angiography offers advantages over functional testing in stable CAD

By Will Boggs MD

NEW YORK (Reuters Health) - Coronary CT angiography (CTA) offers several advantages over functional testing in the evaluation of individuals with stable coronary artery disease (CAD) symptoms, according to results from a Danish nationwide register study.

“The choice of initial testing may knowingly or unknowingly affect the choices that physicians make about downstream patient management,” Dr. Mads E. Joergensen from University of Copenhagen, Denmark told Reuters Health by email. “We believe that physician-awareness of these potential differences is important in everyday clinical practice.”

Noninvasive cardiac testing is the initial step in diagnosing patients with symptoms suggestive of CAD, but the preferred choice of noninvasive testing remains uncertain.

Dr. Joergensen and colleagues used data from Danish national registries to compare outcomes after coronary CTA versus functional testing (exercise electrocardiography and nuclear stress testing), including subsequent use of medications, invasive procedures, and clinical outcomes, in 86,705 patients undergoing initial noninvasive testing for suspected CAD.

Statin therapy was changed significantly more frequently in the coronary CTA group (21.3%) than in the functional testing group (13.4%), as was aspirin therapy (24.9% versus 16.0%, respectively), according to the April Journal of the American College of Cardiology report.

Patients in the coronary CTA group were also more likely to be switched from a regular statin to a potent statin, compared with patients in the functional testing group.

Most patients in both groups did not undergo further testing within 120 days after initial testing. However, downstream noninvasive testing was significantly less frequent after coronary CTA (5.9%) than after functional testing (10.5%). And coronary revascularization was significantly more common in the coronary CTA group than in the functional testing group (for percutaneous coronary intervention, 3.8% versus 2.2%, respectively; for coronary artery bypass graft surgery, 1.3% versus 1.0%, respectively).

Overall, the mean cost of downstream tests, revascularization, statin, and aspirin use within 120 days was significantly higher in the coronary CTA group ($995) than in the functional testing group ($718).

After adjusting for baseline differences, the risk of all-cause mortality was similar in the two testing groups, but the adjusted risk of myocardial infarction (MI) was 29% lower in the coronary CTA group.

In weighted causal inference analyses, coronary CTA was associated with 12% lower risk of all-cause mortality, 36% lower risk of MI, and 19% lower risk of the combined endpoint.

“An initial strategy of coronary CTA to evaluate suspected stable CAD appears to be associated with greater use of preventive cardiac medications and invasive cardiac procedures, including coronary revascularization,” the researchers conclude. “The more intensive clinical management of patients after coronary CTA might ultimately lead to improved clinical outcomes, particularly reductions in acute coronary syndromes.”

“Although consistent with findings from randomized trials, we cannot say if changing the choice of initial testing or downstream management would improve the long-term prognosis,” Dr. Joergensen said.

“Several issues have been discussed in relation to increased use of coronary CT for the evaluation of patient with suspected stable CAD,” Dr. Joergensen said. “As the radiation dose applied by coronary CT continues to decrease, the healthcare costs associated with an approach with initial coronary CT remains to be investigated. A thorough cost-effectiveness analyses assessing these issues is warranted.”

In an editorial, Dr. Ron Blankstein from Brigham and Women’s Hospital, Harvard Medical School, Boston and colleagues write, “The most appropriate way to deal with the incorporation of a new technology that seems to be beneficial, yet costly, is to establish criteria on how to select optimally between the available testing options, rather than assume (as clinical trials sometimes do) that one test is superior across all scenarios.”

“However,” they continue, “the evaluation and management of stable chest pain is complex, and must also rely on institution availability and expertise, the results of previous testing, and patient clinical factors that may affect how the test might influence patient management decisions. Yet, test selection remains highly variable and is often influenced by physician preferences and experience rather than evidence.”

“Thus,” they conclude, “instead of looking for a one-size-fits-all test, we should recognize the tradeoffs inherent in selecting among different tests and strive to identify the best initial testing option, including the identification of those in whom no testing is required.”

Dr. Matthew Budoff from UCLA’s Los Angeles Biomedical Research Institute, Torrance, California told Reuters Health, “I think the reduction of 30% myocardial infarction is important and should be reinforced. This is the same number I demonstrated years ago and the same as a meta-analysis done recently, including large prospective trials such as Promise, ScotHeart, SPARC, and CAPPS. All of these show coronary CTA lowers risk of myocardial infarction and promotes more use of statins and aspirin than functional testing.”

“I think doctors need to consider coronary CTA more in low to intermediate risk patients, given the improved outcomes,” he said by email. “The choice of imaging (type of test, as well as whether any imaging is necessary) is always depending upon local expertise and the individual scenario. One cannot make broad recommendations for groups, as patients are all different.”

“However,” Dr. Budoff concluded, “this adds to the emerging and large literature that favors coronary CTA. Recently, Blue Shield of California and Aetna and Humana all changed their policies to be more favorable to coronary CTA as the preferred test.”

SOURCE: http://bit.ly/2ozCAG5 and http://bit.ly/2nUkITp

J Am Coll Cardiol 2017.

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