Background Patients with acute coronary syndrome and unobstructed coronary arteries represent a clinical dilemma in whom clinical management is uncertain. Cardiovascular magnetic resonance (CMR) has the potential to non-invasively identify the presence of myocardial infarction or acute myocarditis, thus establishing a final diagnosis with management implications.
Aim To assess the diagnostic value of CMR in patients presenting with ACS and unobstructed coronary arteries.
Methods From October 2010 to November 2011, 48 patients who presented with troponin positive ACS and unobstructed coronary arteries were consecutively recruited. A comprehensive CMR protocol, including T2 weighted STIR imaging for oedema and late gadolinium enhancement imaging for myocardial scarring, was performed within 4 weeks of the index event.
Results In 75% of cases, a cause for the troponin rise was found. Based on the oedema and scarring patterns observed, the most common diagnoses were acute myocarditis (Abstract 134 figure 1) in 40% of cases and acute myocardial infarction with spontaneous coronary recanalisation/embolus (Abstract 134 figure 2) in 19% of the cases. In six patients (12%) a diagnosis of cardiomyopathy was established: dilated cardiomyopathy (n=3), hypertrophic cardiomyopathy (n=1) and Tako-Tsubo cardiomyopathy (n=2). Acute pericarditis was present in two patients (4%). The remaining 25% of patients had a normal CMR scan.
Conclusion In the setting of acute coronary syndromes with unobstructed coronary arteries CMR was able to establish a final diagnosis in 75% of patients, identifying acute myocarditis, myocardial infarction with spontaneous recanalisation/embolus, and cardiomyopathies. Establishing a final diagnosis has an important impact in patient management and secondary prevention.
- Acute coronary syndrome
- unobstructed coronary arteries
- cardiac magnetic resonance