Myxoedema coma with complete atrioventricular block: a case report

Advanced atrioventricular (AV) block can accompany severe hypothyroidism, but thyroid dysfunction does not by itself establish reversibility. A 75-year-old man presented approximately 30 minutes after the onset of dizziness and general deterioration. At the initial documented assessment, temperature was 36.6°C, Glasgow Coma Scale score was 15, oxygen saturation was 98% on room air, and blood pressure was 100/60 mmHg while receiving norepinephrine at 0.05 µg/kg/min. The admission electrocardiogram (ECG) showed complete AV block with an atrial rate of approximately 41–42 beats/min and a markedly slow, wide-complex ventricular escape at approximately 13–14 beats/min. Temporary transvenous pacing increased ventricular rate to approximately 80 beats/min, and coronary angiography showed a dominant right coronary artery, non-obstructive plaques, no culprit lesion, and TIMI 3 flow in all major epicardial vessels. Despite effective rate correction, progressive haemodynamic, respiratory and renal deterioration could no longer be explained by the AV block alone, prompting evaluation for an alternative systemic cause. As respiratory failure progressed, SpO2 fell into the 30% range. At controlled endotracheal intubation, blood pressure was 90/60 mmHg during norepinephrine infusion at 0.2 µg/kg/min, while the temporary pacemaker continued to provide ventricular pacing. Cardiac arrest occurred shortly afterwards, with return of spontaneous circulation after approximately 40 minutes of cardiopulmonary resuscitation. After resuscitation, the previously requested thyroid-function results became available and demonstrated severe primary hypothyroidism (TSH 106 mIU/L, fT3 1.18 pg/mL, fT4 0.38 ng/dL); further history revealed approximately one month of levothyroxine non-adherence. The evolving multisystem syndrome yielded a score of 120 under the 2026 joint-consensus adaptation of the Popoveniuc system, highly suggestive of myxoedema coma. Intravenous hydrocortisone and levothyroxine were initiated. Refractory shock and multiorgan failure persisted, and the patient died on day 3. This case highlights that restoring ventricular rate may not correct a concurrent systemic endocrine crisis and that thyroid dysfunction alone does not prove AV-block reversibility.