Stress CMR reduces coronary events in some patients

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Stress cardiac magnetic resonance (CMR) imaging is effective in reducing coronary artery revascularization, hospital readmissions and repeated cardiac testing in intermediate-risk patients with possible acute coronary syndromes (ACS), all without an increase in ACS 90 days after discharge.

These single-center trial findings were published by a team of researchers from Wake Forest School of Medicine in Winston-Salem, N.C., in the July issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.

The authors, led by Chadwick D. Miller, MD, randomly assigned 105 intermediate-risk patients with ACS symptoms to a study group receiving either care in an observation unit (OU) with a stress CMR or usual care from cardiologists or internists. They recruited participants from the emergency department (ED) of Wake Forest Baptist Medical Center over a 67-week period starting in 2011.

The researchers compared the two groups in terms of the primary outcome, which was a combination of coronary artery revascularization, readmission to a hospital and recurrent cardiac testing 90 days later.

“The primary outcome composite at 90 days occurred in 20 participants (38 percent) in the usual care group and 7 (13 percent) in the OU CMR group,” the authors found.

The latter group had significantly fewer revascularizations (2 percent compared with 15 percent of the usual care group), hospital readmissions (8 percent compared with 23 percent) and repeated cardiac testing (4 percent vs. 17 percent).

The OU group also had shorter hospital stays—the average length was 21 hours while in the usual care group, the average was 26 hours.

No OU patients experienced ACS after discharge, but three of the usual care patients did.

Recent studies have highlighted the benefits of CMR for testing ED patients with symptoms related to ACS. Among other things, CMR can diagnose an MI before troponin levels elevate, differentiate between new infarcts and old infarcts and can accurately assess prognosis.

There are economic benefits to CMR as well.

“In intermediate-risk patients, OU-based care with stress CMR testing reduced cost over the course of 1 year compared with an inpatient care strategy in a recent analysis of a single-center randomized trial,” the authors wrote.

The study had limitations, however. The authors utilized only a single-center design and the appropriateness of revascularization was unclear.

“Assessing the net clinical benefit of reducing revascularizations is complicated. Appropriateness criteria for coronary revascularization are intricate and vary on the basis of an individual patient’s clinical data, including angina severity and results from biomarker, invasive, and noninvasive tests,” they wrote.

They added that it was unlikely that anyone who needed revascularization did not undergo it, given the short-term absence of occurrences.

“Longer-term follow-up is being conducted to determine if revascularizations were required after the 90-day period,” they wrote.