Acute myocarditis associated with Graves’ thyrotoxicosis

A 39-year-old man presented with palpitations, tremors, and chest tightness. His past medical history included Graves’ disease for which he had taken carbimazole in the past. Electrocardiogram showed ST-elevation in the inferior leads, troponin-T was elevated at 1168 ng/l (normal <14 ng/l), thyroid-stimulating hormone of <0.01 mIU/l (normal 0.27–4.2 mIU/l), and free T4 of >100 pmol/l (normal 12–22 pmol/l). The patient was commenced on carbimazole, bisoprolol, and a short course of prednisolone following endocrinology review. Cardiovascular magnetic resonance (CMR) was performed to elucidate an underlying cause for the elevated troponin and symptoms. Left ventricular size and systolic function were normal. Myocardial oedema, as indicated by increased signal intensity on T2-weighted imaging, was noted in the basal to mid-inferior, inferolateral, and anterolateral walls. Late gadolinium enhancement (LGE) imaging demonstrated non-ischaemic hyper-enhancement in these segments. These findings were consistent with a clinical picture of acute myocarditis. Repeat CMR was performed at 12 months showing complete resolution of myocardial oedema and a reduction in the intensity and extent of LGE, although residual fibrosis was noted in the basal to mid-inferior, inferolateral, and anterolateral walls. The patient has been well at his subsequent follow-up appointments.