Refractory Ventricular Arrhythmias in Thyrotoxic Periodic Paralysis: An Uncommon Presentation of Cardiogenic Shock.

Thyrotoxic periodic paralysis (TPP) is a rare complication of hyperthyroidism, often seen in young males, characterized by acute flaccid paralysis due to intracellular potassium shifts. While most cases present with isolated muscle weakness, progression to thyroid storm with life-threatening arrhythmias and multiorgan failure is exceedingly rare. We present the case of a previously healthy 23-year-old male who arrived with profound weakness and was found to have severe hypokalemia and suppressed thyroid-stimulating hormone (TSH). Shortly after arrival, he developed ventricular fibrillation and suffered prolonged cardiac arrest, requiring nearly 90 minutes of cardiopulmonary resuscitation. He was placed on extracorporeal membrane oxygenation (ECMO) for refractory cardiogenic shock. His hospital course was further complicated by rhabdomyolysis, acute kidney injury requiring renal replacement therapy, and distal limb ischemia due to femoral cannulation, ultimately necessitating left above-knee amputation and right upper extremity fasciotomy. This case highlights the catastrophic potential of TPP and thyroid storm, the role of early ECMO support in refractory thyrotoxic arrhythmias, and the vascular risks associated with peripheral ECMO cannulation in the critically ill. Prompt recognition and aggressive support remain the cornerstone of survival in endocrine-driven cardiopulmonary collapse.