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SAN DIEGO -- Anatomic CT as the initial screen for suspected stable coronary artery disease didn't improve clinical outcomes compared with functional testing but did increase overall radiation exposure, the PROMISE trial showed.

The composite risk of death, myocardial infarction (MI), hospitalization for unstable angina, or major procedural complications during a median 25 months of follow-up was 3.3% with initial CT angiography (CTA) versus 3.0% with exercise or stress testing (P=0.75), , of Duke University Medical Center, and colleagues found.

Anatomic testing exposed patients to higher overall ionizing radiation exposure through 90 days (mean 12.0 versus 10.1 mSv, P<0.001), in part because nearly one-third initially screened with functional tests got no radiation at all, they reported here at the American College of Cardiology meeting.

But the median per patient exposure was lower with CTA (10.0 versus 11.3 mSv), which , called reassuring in an editorial accompanying simultaneous publication of the trial online in the New England Journal of Medicine.

"Certainly, any concern that radiation doses would be higher with CTA than with functional testing was alleviated by the trial results," wrote Kramer, of the University of Virginia Health System in Charlottesville.

The researchers acknowledged the complex picture on radiation due to the mix of tests in the functional-testing group, some involving radiation and some not.

Still, it's a snapshot of current practice across enrolling sites, and 67.8% of the functional testing group got nuclear stress testing for which the median cumulative exposure was 2.5 mSv higher and the mean exposure 2.1 mSv higher than with CTA, they noted.

"So, no winner was declared," Kramer wrote. "This result prompts the question: How will a tie for CTA change clinical practice?"

'Not Worth It'

These findings "should temper the enthusiastic use of CTA to screen patients with chest pain -- it is not worth the added radiation and use of unnecessary heart caths and stents which did nothing to improve the outcome of patients," commented , of the Henry Ford Hospital in Detroit and a past president of the ACC.

"The current approach of a careful history and stress test yields excellent results without subjecting patients to unnecessary additional procedures and risks that come with CTA," he told 口袋女优.

"This tells me that functional testing -- with stress echo or stress nuclear -- is still the best first step in patients who you are wondering if they have coronary disease," concluded conference chair .

"It also gives you some important information on their exercise capacity and what their symptoms mean," added Poppas, director of the echocardiography lab at Rhode Island Hospital and director of cardiovascular imaging at its Cardiovascular Institute, both in Providence.

There may be a specific set of patients still appropriate for initial CTA, such as those who can't exercise or for whom cardiac catheterization would be undesirable, perhaps due to valve infection or aortic problems, she told 口袋女优 in an interview.

But "wholesale use to replace functional testing has been put to rest," she concluded.

CT angiography was hoped to be a superior tool for outpatient screening due to "the potential to reduce unnecessary invasive testing and improve outcomes, owing to its substantially higher accuracy as compared with functional testing and its unique ability to detect prognostically important but nonobstructive CAD," the researchers noted.

CTA led to fewer catheterizations showing no obstructive CAD -- a prespecified secondary endpoint -- compared with functional testing (3.4% versus 4.3%, P=0.02).

"Although more patients randomly assigned to CTA underwent at least one cardiac catheterization within 90 days after randomization (12.2% versus 8.1% in the functional-testing group) and more patients in the CTA group underwent revascularization overall (6.2% versus 3.2%), including coronary artery bypass grafting, revascularization was not a trial endpoint," the researchers noted.

That will likely be of interest to insurers, many of which have already been balking at reimbursing it over concern that physicians would use it to screen asymptomatic patients, Kramer noted.

Cost Issues

"Comparative cost analysis may be telling, because, generally, the cost of CTA is lower than the cost of stress imaging but higher than that of stress electrocardiography," Kramer added.

A comparative economic analysis of PROMISE looking at the initial test technical costs, hospital-based facility costs, and physician professional fees for testing and hospital services revealed that functional testing was less expensive by an estimated mean $279 in the first 90 days and by $694 by 3 years.

That didn't come out to a significant difference for this intermediate-risk population, , director of outcomes research at the Duke Clinical Research Institute, told attendees.

"The trend toward higher costs with CTA was driven almost completely by more revascularization, and despite reduced use of additional noninvasive testing," he noted.

The analysis didn't include outpatient medications, and quality of life and employment status impacts were still under analysis.

But "since both clinical outcomes and economic outcomes did not differ as hypothesized, cost-effectiveness analysis was not indicated," Mark concluded.

Limitations

While the researchers noted that the pragmatic trial design supported generalizability but they acknowledged it might "limit applicability in settings with tightly controlled population selection, expert noninvasive test performance, or rigorously followed algorithms for subsequent care."

Kramer pointed more to limitations due to the low event rates, "which were driven in part by the high rate of appropriate medical therapy, including statins, in the two groups, as well as the relatively short follow-up period" and that "almost half the events were hospitalizations for unstable angina, which is the softest of the endpoints in the composite."

The trial did end up with the intended intermediate level of risk (53% mean pretest likelihood of coronary artery disease), although the event rate was lower than predicted. The primary composite outcome occurred in 164 of 4,996 patients in the CTA group versus 151 of 5,007 with functional testing during a median 25 months of follow-up.