Cardiac MR’s AUC may need to upgrade some indications

An assessment of appropriate use criteria (AUC) for stress cardiac MR adds weight to the argument that some shuffling is in order in the “maybe appropriate” category. The findings are timely, given an approaching deadline that could impact reimbursement.

In a study published online May 15 in the Journal of Cardiovascular Magnetic Resonance, Sloane McGraw, DO, of the University of Illinois at Chicago, and colleagues explored the downstream use of angiography and revascularization based on the 2013 AUC. The AUC include 80 clinical indications that experts ranked as appropriate, maybe appropriate and rarely appropriate.

In 2017, ordering physicians will be required to certify that they checked the AUC in order to be reimbursed for advanced imaging by Medicare, and their claims will need to include an item about adherence. The Centers for Medicare & Medicaid Services has been tasked with selecting the AUC by this November, according to the authors.

McGraw et al enrolled 300 patients at one institution who were referred for cardiac MR stress testing. Two cardiologists reviewed the clinical information accrued before the stress test and listed the tests as appropriate, maybe appropriate or rarely appropriate based on the 2013 AUC guidelines. After their cardiac MR tests, patients were followed for two months to track the use of angiography and revascularization.

Almost half of the stress cardiac MRs were classified as appropriate while 36.7 percent were considered maybe appropriate and 13.6 percent rarely appropriate. The appropriate and maybe appropriate categories had a higher percentage of abnormal stress results compared with rarely appropriate (29.5 percent, 28.2 percent and 14.6 percent, respectively).

Ischemia was more likely to be detected in the appropriate and maybe appropriate groups than in the rarely appropriate group (18.8 percent, 21.8 percent and 4.8 percent, respectively).  The appropriate and maybe appropriate groups had similar rates for catheterization referral (around 10 percent) while the rate for the rarely appropriate group was 2.4 percent.

Of those, 53.3 percent and 36.4 percent of the appropriate and maybe appropriate groups then received revascularization compared with none in the rarely appropriate group. Detecting ischemia on the stress cardiac MR resulted in catheterization referral in half of the appropriate and one third of the maybe appropriate groups and none of the rarely appropriate group.

The AUC classification for rarely appropriate cardiac MR stress tests seems spot on, based on the fact that none of the patients in the rarely appropriate group went on to receive revascularization, they suggested.  

“We found that studies that were classified as maybe appropriate had similar rates of ischemia and led to similar rates of downstream catheterization and revascularization as those that were deemed appropriate,” McGraw et al wrote. “This suggests that consideration could be given to upgrading some of the common maybe appropriate indications to the appropriate category.”

They described their findings as preliminary.