Stress Cardiac Magnetic Resonance Imaging in Intermediate-Risk Emergency Department Patients with Abnormal High-Sensitivity Troponin.

Background: Patients presenting to the emergency department (ED) with chest pain often have abnormal high-sensitivity troponin (hsTn). However, only about 5% have an acute coronary syndrome. We aimed to assess the safety, feasibility and utility of a clinical disposition protocol including outpatient observation with stress cardiac-magnetic-resonance (CMR) in intermediate-risk patients with abnormal hsTn of unclear etiology.

Methods: Patients with abnormal hsTn and modified HEART-score≤6 underwent CMR to inform diagnosis, risk-stratification, and ED-disposition. Patients were followed at 30 and 90 days for all-cause mortality, readmission for myocardial infarction, and unplanned coronary revascularization.

Results: CMR was completed in 50 patients (64 years, 56% male) at a median of 23.2hours after presentation to the ED. CMR findings of coronary-artery-disease (CAD) were present in 19 (38%) of patients, of which 13 had known CAD and 6 received a new diagnosis of CAD. In 12 (24%) patients, cardiac noncoronary-artery-disease was diagnosed [cardiomyopathy (8), valvular disease (3), myocarditis/pericarditis (1)], of which the majority (83%) were new diagnoses. CMR was normal in 19 (38%) patients. After CMR results were reported, the decision to admit was made in 10 (20%) patients, while 40 (80%) were discharged from the ED without further cardiac testing. Follow-up was completed in 96% of patients, of which no patients experienced an adverse event.

Conclusion: A disposition protocol with outpatient observation and stress-CMR is feasible and useful for determining the etiology of myocardial injury and risk-stratification in patients presenting to the ED with chest pain, abnormal hsTn, and intermediate risk.