Calcified and noncalcified plaque by CCTA. Source: Fabian Bamberg, MD, University of Munich

Medicare beneficiaries who underwent coronary computed tomography angiography (CCTA) in a nonacute setting were more likely to undergo subsequent invasive cardiac procedures and have higher coronary artery disease (CAD) spending than patients who underwent stress testing, according to a study published in the Nov. 16 issue of the Journal of the American Medical Association.

Jacqueline Baras Shreibati, MD, of the Stanford University School of Medicine in Stanford, Calif., and colleagues wanted to compare utilization and spending on functional and anatomical noninvasive cardiac testing among Medicare beneficiaries. The effect of the noninvasive CCTA diagnostic test on subsequent clinical management had not been previously established.

The researchers performed a retrospective, observational cohort study of claims data from a 20 percent random sample of more than 280,000 Medicare fee-for-service beneficiaries age 66 or older. Claims were from 2005 to 2008 and the beneficiaries studied had no claims for CAD in the preceding year.

Results showed CCTA was associated with an increased likelihood of cardiac procedures when compared with stress myocardial perfusion scintigraphy (MPS). CCTA led to subsequent cardiac catheterization in 22.9 percent of cases, compared with 12.1 percent for MPS. Rates of percutaneous coronary intervention (7.8 percent versus 3.4 percent) and coronary artery bypass graft surgery (3.7 percent versus 1.3 percent) were also higher among patients who underwent CCTA.

CCTA was associated with an average increase of $4,200 in total healthcare spending, which the authors noted as almost entirely attributable to payments for any claims for CAD.

“Our data suggest that increased use of CCTA may greatly increase subsequent diagnostic testing and invasive cardiac procedures,” wrote the authors.

At 180 days, there were similar likelihoods for mortality and a slightly lower likelihood of hospitalization for acute myocardial infarction among patients who underwent CCTA compared with those who underwent MPS.

The researchers wrote that a complete evaluation of CCTA use must include its potential associated benefits as well as its impact on healthcare spending. Along those lines, they noted that one of the limitations of the study is that it did not include a long-term follow-up to assess the effects of CCTA on cardiac events.

“In particular, any improvement in survival attributable to the higher use of [coronary artery bypass graft] surgery among the CCTA group would be unlikely to become evident for several years, even if [coronary artery bypass graft] surgery were performed for left main coronary artery disease,” wrote the authors. “The available data on acute MI and all-cause mortality within 180 days of the index test provide a limited picture of their association with mode of noninvasive testing.”

Since it was first reimbursed, the number of CCTA procedures among Medicare beneficiaries has increased steadily, from 38,171 in 2006 to more than 78,000 in 2008, according to Shreibati et al. While it only makes up about 3 percent of noninvasive testing for CAD in the U.S., a substantial increase in use is likely over the next decade.

“The increased use of invasive procedures and the higher spending on care after CCTA documented in this study suggest that clinicians and policymakers should critically evaluate the use of CCTA in clinical practice, based on studies of subsequent outcomes,” concluded the authors.