Impact of untreated hypothyroidism on the cardiac conduction system: a case report and review of pathophysiology

Background. Third-degree atrioventricular (AV) block, also referred as complete heart block, results from the complete disruption of impulse transmission between the atria and ventricles, leading to desynchronized electrical activity. Among the numerous causes involved in the development of an AV block, severe hypothyroidism is one of the rarest. Case Report. We documented the case of a 77-year-old female patient diagnosed with severe hypothyroidism alongside a complete atrioventricular (AV) block. Conclusions. Evaluating thyroid function is essential whenever a patient is diagnosed with a high-degree AV block, as severe hypothyroidism could potentially be the underlying factor.