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CMR Before Invasive Coronary Angiography in Suspected NSTEMI
Quick Takes
- Early CMR prior to an invasive coronary angiogram (ICA) in patients presenting with NSTEMI is feasible and may result in changes in diagnosis and/or management in nearly half of patients.
- Only approximately one in four patients with MINOCA have an infarct on CMR. The remainder have alternative nonischemic etiologies or normal CMRs.
- Infarct-related arteries may be reclassified in as many as one in nine patients using CMR.
Study Questions:
Is early cardiac magnetic resonance (CMR) prior to an invasive coronary angiogram (ICA) in patients with suspected non–ST-segment elevation myocardial infarction (NSTEMI) useful?
Methods:
This was a prospective single-center study of patients with suspected acute NSTEMI. Early CMR was performed prior to ICA (including gated imaging, T1 mapping, T2 imaging, and late gadolinium enhancement) and interpreted blinded to ICA. CMR and ICA findings were correlated. Clinical teams were also blinded to CMR until after ICA.
Results:
CMR was performed at a median of 33 hours [IQR 20-48 hours] after admission and 4 hours [IQR 2-6 hours] pre-ICA. On CMR, 52% of patients had subendocardial infarction, 15% had transmural infarction, and 18% had a nonischemic finding such as myocarditis, or stress-related or other cardiomyopathy. In addition, 11% of CMR scans were normal and 4% were nondiagnostic. Of the 27 patients with nonobstructive coronary artery disease (CAD) on ICA, MI was found on CMR in 22% (6 out of 27). The remaining presumptive MI with nonobstructive coronary arteries (MINOCA) diagnoses were reclassified by CMR as nonischemic etiologies in 11 out of 27 MINOCA cases. In addition, among patients where obstructive CAD was found at ICA, the infarct artery was reclassified in 7 out of 61 cases (11%).
Conclusions:
Significant changes in diagnosis and/or management may occur in as many as half of patients who present with suspected NSTEMI if early CMR is used to identify infarct arteries and alternative etiologies.
Perspective:
This study prospectively demonstrates the value of early CMR in patients with suspected NSTEMI. This extends prior studies, which have demonstrated that CMR can identify MI and nonischemic etiologies in many patients with MINOCA. This study demonstrates that only a minority of these patients have infarct findings on CMR. Most have nonischemic or normal findings. Further, it has been long known that it can be challenging to identify infarct arteries in some patients. In this study, nearly one in nine patients had reclassification of the infarct artery, suggesting that there could be early value to CMR even in patients with clear evidence of NSTEMI (as opposed to MINOCA).
Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Vascular Medicine, Interventions and Imaging, Interventions and Vascular Medicine, Angiography, Magnetic Resonance Imaging, Nuclear Imaging, Chronic Angina, Acute Heart Failure
Keywords: Magnetic Resonance Imaging, Coronary Angiography, Non-ST Elevated Myocardial Infarction
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