Case Report: Bilateral coronary ostial spasm triggered by iatrogenic thyrotoxicosis mimicking left main coronary artery disease

Background: Thyrotoxicosis is associated with enhanced sympathetic activity and increased coronary vasomotor reactivity. However, bilateral coronary ostial spasm mimicking critical left main coronary artery disease is rare. Case summary: A 61-year-old woman presented with a 3-day history of exertional chest pain. She had undergone total thyroidectomy 18 years earlier and was receiving levothyroxine 75 μg daily. One month prior, carvedilol 6.25 mg twice daily had been initiated for palpitations. Treadmill testing demonstrated ST-segment elevation in aVR and anterior leads with reciprocal ST depression in inferior leads. Emergent coronary angiography revealed severe ostial narrowing of both the left main (LM) and right coronary artery (RCA), raising suspicion of critical multivessel disease. However, complete resolution of both lesions following intracoronary nitrate administration confirmed bilateral coronary vasospasm. Laboratory evaluation showed suppressed TSH (0.07 mIU/L) with markedly elevated free T4 and free T3 levels, consistent with iatrogenic thyrotoxicosis. Levothyroxine dose reduction, discontinuation of carvedilol, and initiation of calcium channel blocker therapy resulted in complete symptom resolution. Conclusion: -blocker selection are critical to avoid unnecessary revascularization.