A 59-year-old female from India with Graves' Disease, managed on 20mg of carbimazole, was admitted with non-ST elevated myocardial infarction(NSTEMI). She presented with chest pain, elevated troponin (2034ng/L), and inferolateral ischaemic ECG changes. Examination showed tachycardia (100-110 beats/minute) and a smooth, non-tender goitre with a bruit.
Thyroid function tests indicated thyrotoxicosis, with TSH 0.00mU/L [0.55-4.75mU/L], fT4 60.6pmol/L [11.5-22.7pmol/L], and fT3 30pmol/L [2.5-6.5pmol/L]. TSHrAbs were positive 14IU/L [<1.8IU/L]. Echocardiogram showed inferior regional wall motion abnormalities and a mildly to moderately dilated left ventricle, with normal systolic function (LVEF 54%) and no atrial dilatation.
Initial management for thyrotoxicosis included Carbimazole 15mg TDS, glucocorticoids, Lugol's iodine 0.5mL TDS, and Metoprolol 25mg BD. NSTEMI treatment comprised Aspirin 100mg daily, Ticagrelor 90mg BD, and Atorvastatin 40mg daily, with Fondaparinux 2.5mg daily before angiography. Hypertension was managed with Amlodipine 10mg and Perindopril 2.5mg daily.
Four days later, an angiogram (12g iodine administered) was performed. Seven days from initial results, fT4 decreased to 26.5pmol/L and fT3 to 7.6pmol/L. The angiogram revealed severe triple vessel disease, necessitating coronary artery bypass grafting.
Managing acute coronary syndrome (ACS) in the context of thyrotoxicosis presents challenges. Thyrotoxicosis can exacerbate cardiac ischaemia with associated tachycardia increasing myocardial oxygen demand and impairing coronary flow(1). Cardiac arrhythmias, more common in thyrotoxicosis, may complicate post-ACS management(2,3).
Revascularisation via angiogram is essential for ACS, but iodine-based contrast agent use comes with concerns it may worsen thyrotoxicosis or trigger a thyroid storm. Though usually a suppressant of thyroid hormone, iodine use can result in the Jod-Basedow effect, and the less common but highly concerning thyrotoxic Wolff-Chaikoff escape phenomenon which can cause refractory disease only amenable to surgery(4). Balancing the benefits of Lugol's iodine administration pre-angiography with these risks is complex.
Despite these issues, literature is limited, with few case reports and no consensus on optimal management strategies.