Background:

Patients hospitalized with suspected ST-segment elevation myocardial infarction (STEMI) who have normal coronary arteries (CAs) on invasive coronary angiography (ICA) may have an AMI or another acute cardiac disease that mimics it.

Aim:

To evaluate the usefulness of cardiac magnetic resonance imaging (CMRI) for diagnosing conditions resembling AMI with normal CAs.

Material and Methods:

We studied 424 consecutive patients admitted with suspected STEMI who underwent ICA. Those with normal CAs underwent CMRI involving cine-CMRI sequences to evaluate segmental wall motion, T2-weighted short-tau inversion-recovery imaging to detect oedema and delayed contrast enhancement (DCE) after gadolinium administration to identify necrosis/fibrosis. Patients with previous myocardial infarction were excluded.

Results:

Twenty-six patients (6.1%) had normal CAs. Definitive diagnosis after CMRI was acute myocarditis in 11 patients (42.3%) whose DCE was localized in the subepicardium or intramyocardially but not in the endocardium, AMI in nine patients (34.6%) who had subendocardial or transmural DCE, and Takotsubo cardiomyopathy (TCM) in six patients (23.1%), whose CMRI showed regional contractility abnormalities of the left ventricle and myocardial oedema but not DCE.

Conclusions:

Cardiac magnetic resonance imaging allows a precise diagnosis of acute myocardial infarction in patients with angiographically normal coronary arteries.