Timing of cardiovascular magnetic resonance imaging and diagnostic yield in patients with acute myocardial infarction with nonobstructive coronary arteries

Abstract Background Accurate diagnosis of the underlying cause of myocardial infarction (MI) without obstructive coronary artery disease (MINOCA) is crucial. Cardiovascular magnetic resonance (CMR) plays an important role in the work up of patients with MINOCA. However, the timing of performance of CMR may impact on the diagnosis yield. Purpose To establish the diagnostic yield of CMR in a large cohort of patients admitted with MINOCA based on the timing of referral to CMR. Methods All patients referred to CMR from January 2009 to February 2022 with MINOCA were included. Studies were performed on a 1.5 T or 3T scanners. SSFP cines, T2-weighted black-blood fat-sat images and DE-segmented GE IR images 10–15 minutes after iv gadolinium-DTPA administration (0.15mmol/kg) were performed in 3 long-axis and 11–15 parallel short-axis views. All images were reviewed and analyzed off-line with specialized post-processing software. Results A total of 203 patients (median age 49 years, 60% men) with MINOCA diagnosis were included. Main ECG alterations were ST-segment elevation (STE) (57%) and T wave inversion (19%). Mean peak high sensitivity (HS)-TnI levels were 3706pg/mL. Median time to CMR was 7 days (5–9 days). Mean LVEF was 58% (range 18–83%) and mean LVEDVi 77 mL/m2 (range 35–210 mL/m2). Regional wall abnormalities were present in 123 patients (62%). High signal in T2w images was detected in 153 cases (75%) and late gadolinium enhancement (LGE) in 143cases (71%). Final CMR diagnosis resulted in myocarditis in 46%, MI in 20%, Takotsubo in 18%, and other cardiomyopathies in 6.4%. CMR was normal in 15 patients and not conclusive in 1. When CMR was performed within 7 days of admission (median: 5 days (4–6 days); n: 116 patients), the distribution of diagnoses was myocarditis in 53%, MI in 20%, Takotsubo in 16%, other cardiomyopathies in 6% and normal CMR in 4%. Whereas, if CMR was performed after 7 days (median: 10 days (8–12 days); n: 87 patients), the diagnoses were as flows: myocarditis in 36%, MI in 22%, Takotsubo 20%, cardiomyopathies in 7%, not conclusive in 1% and normal CMR in 13% (Table 1). Conclusions CMR led to the underlying diagnosis of MINOCA in 92% of patients. Myocarditis was the most frequent diagnosis. The final diagnosis of myocarditis was more frequent when CMR was performed within 7 days with a lesser percentage of normal CMR. Funding Acknowledgement Type of funding sources: None.