HYPERTHYROIDISM MASQUERADING AS ACUTE MYOCARDIAL INFARCTION

Abstract

INTRODUCTION/BACKGROUND
Troponin-Positive Non-Obstructive Coronary Arteries (TpNOCA) are conditions characterized by elevated troponin levels accompanied by absent obstructive coronary artery disease (CAD) as observed on coronary angiography. It encompasses both coronary and noncoronary causes of myocardial injury.

CASE
A 31-year-old female with no known medical illness presented with fever, vomiting and diarrhea for 4 days. She did not have any features or family history of Graves’ Disease. She had no goiter and denied any biotin supplements or illicit drugs. On arrival she had a fever of 38.5°C, palpitations with a pulse ranging between 110–130 beats/min, and a blood pressure of 89/47. She was intubated due to impending respiratory distress. Initial electrocardiogram (ECG) done showed atrial fibrillation (AF). Repeated ECG showed ST-segment elevation over the lateral leads with reciprocal ST depression. High-sensitivity Troponin-T taken on arrival was markedly raised at 957 ng/L, and repeated 2 hours later was 3089 ng/L. Patient was rushed for an emergency angiogram by the cardiology team which revealed unobstructed coronaries. Echocardiography performed was normal.

A thyroid function test (TFT) taken due to AF revealed Free T4 of 33 pmol/L with a suppressed TSH of 0.02 mIU/L. Alanine Aminotransferase (ALT) taken was 383 U/L attributable to ischemic hepatitis. Patient was commenced on carbimazole 10 mg daily with careful daily ALT monitoring. Lugol’s Iodine 10 drops TDS and IV hydrocortisone 100 mg TDS were given for 5 days. Patient eventually improved with normalization of TFT and liver profile with tapering carbimazole dose. TSH-receptor Antibodies (TRAb) taken was negative and we referred this patient for an outpatient thyroid ultrasonography to rule out toxic adenoma.

CONCLUSION
TpNOCA may be induced by hyperthyroidism due to heightened oxygen demand and coronary vasospasm leading to Type-2 myocardial infarction in the presence of unobstructed coronary arteries. Prompt identification and management of hyperthyroidism is crucial to avert severe complications and ensuring a favourable outcome.