Role of Cardiac Magnetic Resonance Imaging and Troponin T in Definitive Diagnosis of Myocardial Infarction With Nonobstructive Coronary Arteries (MINOCA)

Background: It is unknown whether the degree of high-sensitivity troponin T (hsTropT) elevation in patients with suspected myocardial infarction without obstructive coronary arteries (MINOCA) pre-sentations can help predict the likelihood of an abnormal cardiac magnetic resonance (CMR) scan. In this study we describe the diag-nostic utility of CMR in patients with MINOCA and assesses the effect of peak hsTropT levels at presentation on CMR diagnostic yield. Methods: Records of consecutive patients (n = 1407) referred for CMR at a tertiary referral hospital between January 2016 and September 2021 were reviewed. A total of 70 patients met the criteria of MINOCA including ischemic chest pain, elevated peak hsTropT, and nonobstructive coronary artery disease (< 50% stenosis). The peak hsTropT levels within 72 hours of admission were identified. CMR images were generated using a 3.0 T Siemens scanner. Predictors of having an abnormal CMR were evaluated.Results: CMR established a diagnosis in 71% (n = 50) of patients, with the most common CMR diagnosis being myopericarditis (n = 27; 39%). Time to CMR was an independent predictor of a normal CMR scan (odds ratio, 0.98; 95% confidence interval, 0.97-0.999). Peak hsTropT had a high diagnostic accuracy for identifying patients with an abnormal CMR scan (area under the receiver operator characteristic curve, 0.81; P < 0.001). The optimal hsTropT cutoff was 166 ng/L, with 72% sensitivity and specificity. A troponin value > 166 ng/L was independently predictive of an abnormal CMR scan (odds ratio, 4.76; 95% confidence interval, 1.32-17.11).Conclusions: HsTropT and early CMR imaging are independently pre-dictive of an abnormal CMR scan in patients with MINOCA. Addition-ally, the use of a hsTropT cutoff provides incremental predictive value to clinical parameters and time to CMR scanning in determining an abnormal scan.