Background: In patients with myocardial infarction with nonobstructive coronary arteries (MINOCA), cardiovascular magnetic resonance imaging (CMR) can often establish a causal diagnosis. It is unknown if CMR is warranted in patients with normal echocardiographic findings, or if measurement of high-sensitive troponin T (hs-TnT) and NT-pro-BNP can be of value in selecting patients for further imaging. Objectives: To assess the diagnostic accuracy of echocardiography and hs-TnT and NT-pro-BNP for identifying patients receiving any diagnosis using CMR. Methods: We included patients (n=123) from the SMINC2 study who underwent same day CMR and echocardiography, at a median of 3 days after hospital admission for MINOCA. Normal echocardiography was defined as left ventricular ejection fraction ≥55%, absolute global longitudinal strain ≥17%, E/e′≤14, and no regional wall motion abnormalities. Logistic regression models were fitted to assess the probability of CMR diagnosis at increasing levels of hs-TnT and NT-pro-BNP. Results: Of patients with a normal echocardiographic examination, 23/33 (70%) received a diagnosis using CMR. Pathological echocardiography identified patients with a diagnosis using CMR with a sensitivity of 77%, specificity 38%, positive predictive value 82%, and negative predictive value 30%, respectively. There was no level of hs-TnT or NT-pro-BNP below which a CMR diagnosis could be reliably excluded. Conclusions: The majority of patients with MINOCA and a normal echocardiogram will receive a diagnosis by CMR. A CMR diagnosis was common even among patients with low levels of biomarkers. CMR should be recommended regardless of echocardiographic findings and hs-TnT or NT-pro-BNP levels in patients with MINOCA.

The authors have declared no competing interest.

This work was supported by the Swedish Research Council (grant no. 2013-02190), Stockholm county council (grant no. 20150051, 20170053), and the Swedish Heart and Lung Foundation (grant no. 20150612, 20150423, 20170669).

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Stockholm Regional Board of Ethics (2014/131-31/1, 2014/1546-32) gave ethical approval for this work.

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