Thyrotoxicosis is associated with increased cardiovascular morbidity and mortality, primarily due to heart failure and thromboembolism. However, the relationship between thyroid hormone excess and the cardiac complications of angina pectoris and myocardial infarction remains largely speculative. Moreover, few studies have been reported on the effect of thyroid hormone levels within normal range on coronary artery disease (CAD). Thyroid hormones may directly influence myocardial oxygen supply and demand and cause a critical imbalance resulting in angina pectoris and myocardial infarction 1 . We present the case where acute MI was an initial presentation of thyrotoxicosis in a young man of 30 years of age who had been entirely fit & well prior to this acute coronary event.CASE REPORT: A 30 year old male patient presented with sudden onset sub-sternal, squeezing nature chest pain radiating to the left arm with palpitations, sweating and tremors for last 2 hours. No associated history of exertion, fever, coughs, dyspnoea or heat intolerance. No history of diabetes, hypertension, dyslipidaemia or any other chronic disorder. Family history was insignificant. He did not use drugs or alcohol, and except for a history of smoking cigarette quarter of pack per year, he had healthy attributes.On Physical examination the blood pressure-130/80mmHg, heart rate-100bpm, BMI-24.6 with normal jugular venous pressure and carotid pulse. The head and neck examination were normal, no exophthalmos. Cardiac auscultation was within normal limits except for the tachycardia. No murmurs heard. Other systemic examination was within normal limits.Urgent ECG done which revealed ST segment elevation with T wave inversion in anterior leads. Patient was loaded with aspirin, clopidogrel and atorvastatin as an urgent measure and admitted.Laboratory investigations revealed normal electrolytes and kidney function test. Complete blood count was normal with slightly deranged LFT [S. bilirubin T-2.2, D-1.3, SGOT-188, SGPT-71, ALP 173] and Plasma Lipids (Total cholesterol 127mg/dl, HDL 36mg/dl, LDL 77.2mg/dl, VLDL 13.8mg/dl, Triglycerides 69mg/dl). Random blood sugar was 212mg/dl. CK-MB was 30.2ng/ml (Normal: 0.6-6.4ng/ml).2D echo shows LVEF 45% with mild LV dysfunction. Emergency coronary angiography was performed. This revealed a massive spasm of left anterior descending (LAD) coronary artery. There was critical narrowing of the LAD (70%) in apical segment with possible superimposed thrombus. Primary PTCA was advised. Recanalization LAD was successfully done. He was started on standard medication used in patients after myocardial infarction (Aspirin, clopidogril, acitrom, cardarone, lvabradin, rosuvastatin). Post PTCA echocardiography was done which showed regional wall motion abnormality with mild impairment of LV function and mild MR. He continued to have tachycardia and tremors. Thyroid function test was advised. It revealed free-T4 7.8 (Normal: 3.1-6.8pmol/l), free-T3 34.96 (Normal: 12.0-22.0pmol/l) and TSH 0.034 (Normal: 0.274.2IU/ml),
