Initial Imaging-Guided Strategy Versus Routine Care in Patients With Non–ST-Segment Elevation Myocardial Infarction

Abstract

BackgroundPatients with non–ST-segment elevation myocardial infarction and elevated high-sensitivity cardiac troponin levels often routinely undergo invasive coronary angiography (ICA), but many do not have obstructive coronary artery disease. ObjectivesThis study investigated whether cardiovascular magnetic resonance imaging (CMR) or computed tomographic angiography (CTA) may serve as a safe gatekeeper for ICA. MethodsThis randomized controlled trial (NCT01559467) in 207 patients (age 64 years; 62% male patients) with acute chest pain, elevated high-sensitivity cardiac troponin T levels (>14 ng/l), and inconclusive electrocardiogram compared a CMR- or CTA-first strategy with a control strategy of routine clinical care. Follow-up ICA was recommended when initial CMR or CTA suggested myocardial ischemia, infarction, or obstructive coronary artery disease (≥70% stenosis). Primary efficacy and secondary safety endpoints were referral to ICA during hospitalization and 1-year outcomes (major adverse cardiac events and complications), respectively. ResultsThe CMR- and CTA-first strategies reduced ICA compared with routine clinical care (87% [p = 0.001], 66% [p < 0.001], and 100%, respectively), with similar outcome (hazard ratio: CMR vs. routine, 0.78 [95% confidence interval: 0.37 to 1.61]; CTA vs. routine, 0.66 [95% confidence interval: 0.31 to 1.42]; and CMR vs. CTA, 1.19 [95% confidence interval: 0.53 to 2.66]). Obstructive coronary artery disease after ICA was found in 61% of patients in the routine clinical care arm, in 69% in the CMR-first arm (p = 0.308 vs. routine), and in 85% in the CTA-first arm (p = 0.006 vs. routine). In the non-CMR and non-CTA arms, follow-up CMR and CTA were performed in 67% and 13% of patients and led to a new diagnosis in 33% and 3%, respectively (p < 0.001). ConclusionsA novel strategy of implementing CMR or CTA first in the diagnostic process in non–ST-segment elevation myocardial infarction is a safe gatekeeper for ICA.