We report a case of myocarditis mimicking acute lateral myocardial infarction and treated as such initially, which was complicated by ventricular fibrillation a few hours after admission to the intensive care unit. The correct diagnosis was rapidly made using a low-dose delayed-enhanced cardiac multidetector computed tomography scan performed immediately after a normal coronary angiogram, demonstrating typical myocardial late hyperenhancement and good correlation with delayed enhanced magnetic resonance imaging. This case suggests that myocarditis can be accurately diagnosed by delayed-enhanced cardiac multidetector computed tomography in an emergency setting. The other lesson from this case is that patients presenting with severe clinical symptoms, important ECG signs and high myocardial enzyme levels should be closely monitored for at least 72 hours, even when myocardial infarction has been excluded.