Myocardial infarction masquerading as myocarditis in a patient with factor V Leiden: unmasked with MR.

We present a case of a 21-year-old man presenting with sharp left-sided chest pain. A CT pulmonary angiogram was negative, ECG was unremarkable and a mild troponin rise was observed. Myocarditis was suspected as the most likely diagnosis, particularly in view of the patient's previous diagnosis of myocarditis 3 years prior. A cardiac MRI was indicative of an acute mid-anterior myocardial infarction (MI) and an old inferior MI with an associated aneurysm. A subsequent angiogram revealed a subtotal occlusion in the second diagonal artery, likely precipitated by homozygous factor V Leiden.This case illustrates the value of MRI in differentiating acute MI from myocarditis when clinical suspicion is low, as in this young patient with atypical chest pain. Further, it demonstrates the value of MRI in detecting previous MIs and reinforces the importance of searching for precipitants of MI in young patients.