Trial results published in JACC: Cardiovascular Imaging  suggest that managing patients at intermediate risk for acute coronary syndromes (ACS) in an observation unit and testing them with stress cardiac magnetic resonance (CMR) imaging reduces the rates of hospital readmission, recurrent cardiac testing and coronary artery revascularization, without increasing post-discharge ACS at 90 days after randomization.

The randomized, single-center clinical trial compared the management strategy to usual in-hospital care. It randomized 105 intermediate-risk participants recruited from an emergency department with symptoms suggestive of ACS, including acute chest pain and related symptoms, but without ACS as assessed on the basis of electrocardiogram and troponin levels, to usual in-patient care provided by cardiologists and internists or care in an observation unit that included stress CMR testing.

The 52 patients treated in an observation unit with stress CMR testing had significantly reduced rates of hospital readmissions (8 percent versus 23 percent, p = 0.03) and recurrent cardiac testing (4 percent versus 17 percent, p = 0.03). The observation unit patients also also had fewer revascularization procedures compared with the 53 patients who received usual in-hospital care (2 percent versus 15 percent, p = 0.03). In all, seven of the 52 patients treated in an observation unit with stress CMR experienced these primary outcomes compared with 20 of the 53 patients given usual in-hospital care (p = 0.006).

In addition, the median length of stay for patients in the observation unit group was 21 hours versus 26 hours for patients in the usual care group (p < 0.001). Following discharge, ACS occurred in three patients in the usual care group and no patients in the observation unit group.

Patients who were managed in the observation unit setting underwent serial troponin measurements at four hours and eight hours after initial evaluation on arriving in the unit, and stress CMR exams at the first available time after arrival. The treating physicians determined the care for patients managed in-hospital.

"These very preliminary findings suggest that highly accurate, noninvasive testing may aid in the selection of patients for invasive testing and revascularization," the study's authors conclude.

Keywords: Acute Coronary Syndrome, Chest Pain, Patient Readmission, Tomography, Electrocardiography, Coronary Vessels, Magnetic Resonance Spectroscopy, Hirudins, Troponin, Exercise Test