Early versus late cardiac magnetic resonance in the diagnosis of myocardial infarction with non-obstructive coronary arteries

Introduction and objectives

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is responsible for about 10% of all acute myocardial infarctions (AMI). Therapeutic strategies and prognosis depend on the underlying etiology, and a multimodal approach is essential. The objectives of this study were to characterize the group of patients diagnosed with MINOCA and to valuate the diagnostic yield of cardiovascular magnetic resonance (CMR).

Methods

This was a retrospective, observational, and analytical study, including 516 patients admitted for a non-ST-elevation MI and with no significant coronary disease on coronary angiography between January 2016 and September 2021.

Results

After the inclusion criteria, 163 patients remained of the 516 admitted to the study. They were divided into four groups based on the CMR results: MINOCA (n=51), Takotsubo syndrome (n=37), myocarditis (n=33), and without diagnosis (n=42). Most patients diagnosed with MINOCA were female with a mean age of 61.06±13.83 years. CMR identified the diagnosis in 74.2% of patients admitted for suspected acute MI, in which coronary angiography showed the absence of significant obstructions. The median time between hospital admission and CMR was significantly shorter in the groups that had a diagnosis compared with the group with no diagnosis (p=0.038), with a significant increase in diagnostic profitability if CMR was performed up to 14 days after admission (p=0.022). There were no deaths of cardiovascular etiology during the follow-up period.

Conclusions

CMR was fundamental as it identified the diagnosis in three out of four patients; it should be performed in the first 14 days.