Background In patients presenting with acute cardiac
symptoms, abnormal ECG and raised troponin,
myocarditis may be suspected after normal angiography.
Aims To analyse cardiac magnetic resonance (CMR)
findings in patients with a provisional diagnosis of acute
coronary syndrome (ACS) in whom acute myocarditis
was subsequently considered more likely.
Methods and results 79 patients referred for CMR
following an admission with presumed ACS and raised
serum troponin in whom no culprit lesion was detected
were studied. 13% had unrecognised myocardial
infarction and 6% takotsubo cardiomyopathy. The
remainder (81%) were diagnosed with myocarditis.
Mean age was 45615 years and 70% were male. Left
ventricular ejection fraction (EF) was 58610%;
myocardial oedema was detected in 58%. A myocarditic
pattern of late gadolinium enhancement (LGE) was
detected in 92%. Abnormalities were detected more
frequently in scans performed within 2 weeks of
symptom onset: oedema in 81% vs 11% (p<0.0005),
and LGE in 100% vs 76% (p<0.005). In 20 patients with
both an acute (<2 weeks) and convalescent scan
(>3 weeks), oedema decreased from 84% to 39%
(p<0.01) and LGE from 5.6 to 3.0 segments (p¼0.005).
Three patients presented with sustained ventricular
tachycardia, another died suddenly 4 days after
admission and one resuscitated 7 weeks following
presentation. All 5 patients had preserved EF.
Conclusions Our study emphasises the importance of
access to CMR for heart attack centres. If myocarditis is
suspected, CMR scanning should be performed within
14 days. Myocarditis should not be regarded as benign,
even when EF is preserved.