A randomized trial found that patients with suspected coronary heart disease who underwent cardiovascular magnetic resonance (CMR)–guided care had a significantly lower probability of unnecessary angiography within 12 months compared with patients who received National Institute for Health and Care Excellence (NICE) guidelines–directed care. The difference was not statistically different between CMR-guided care and myocardial perfusion scintigraphy (MPS)–guided care.

After a year, the rates of major adverse cardiovascular events and disease detection were similar among patients who received CMR-guided care, NICE guidelines-directed care and MPS–guided care.

Lead researcher John P. Greenwood, PhD, of the University of Leeds in the U.K., and colleagues published their results online in JAMA on Aug. 29.

The findings were also presented at the European Society of Cardiology’s Congress in Rome.

“Rates of invasive angiography are considered too high among patients with suspected coronary heart disease,” Greenwood said in a news release. “Our findings show that both (CMR) and (MPS) significantly reduced rates of unnecessary angiography compared to guideline-directed care, with no penalty in terms of major adverse cardiovascular events. This suggests that functional imaging should be adopted on a wider basis, even in high-risk patient subgroups.”

The researchers mentioned that MPS by single-photon emission computed tomography was the most common test to assess myocardial ischemia. They added that CMR was becoming more popular and had diagnostic accuracy and prognostic value. MPS-guided care follows the American College of Cardiology Foundation and American Heart Association appropriate use criteria.

In this trial, known as CE-MARC 2 (Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease 2), the researchers enrolled 1,202 patients with suspected angina pectoris who were at least 30 years old, had a coronary heart disease pretest likelihood of 10 percent to 90 percent and were suitable for revascularization.

Patients were randomized at six hospitals in the U.K. in a 1:2:2 ratio to management according to NICE guidelines, CMR-guided care or MPS-guided care. The mean age was 56.3 years old, and 46.5 percent of patients were women. The mean coronary heart disease pretest likelihood of coronary heart disease was 49.5 percent.

After 12 months, 49.5 percent of patients in the NICE guidelines group, 17.7 percent of patients in the CMR group and 16.2 percent of patients in the MPS group had invasive coronary angiography.

Unnecessary angiography occurred in 28.8 percent of patients in the NICE guidelines group, 7.5 percent of patients in the CMR group and 7.1 percent of patients in the MPS group. The researchers defined unnecessary angiography as a normal fractional flow reserve or quantitative coronary angiography value in all coronary vessels that were 2.5 mm or greater in diameter. The definition included unnecessary angiography occurring after a false-positive result, patients with high coronary heart disease pretest likelihood who were sent directly to coronary angiography (in the NICE guidelines group only) and imaging results that were inconclusive or negative by overruled by the responsible physician.

A major adverse cardiovascular event within 12 months occurred in 1.7 percent in patients in the NICE group, 2.5 percent of patients in the CMR group and 2.5 percent of patients in the MPS group. The researchers defined major adverse cardiovascular events as cardiovascular death, MI, unplanned coronary revascularization and hospital admission for cardiovascular cause.

The researchers cited a few potential limitations of the study, including the presence of false-positive and false-negative rates. The trial also enrolled mostly white northern European participants, so the results might not be generalizable to other patient populations. In addition, this study did not evaluate quality of life and cost-effectiveness analyses, although the researchers said they are currently collecting and analyzing such data.

“These results show that a broader use of functional imaging (CMR or MPS), in low, intermediate and high risk patient groups, could reduce the rates of invasive angiography that ultimately show no obstructive coronary disease,” Greenwood said. “In addition, CE-MARC and CE-MARC 2 further support the role of CMR as an alternative to MPS for the diagnosis and management of patients with suspected [coronary heart disease].”