An Unusual Cause of Completely Reversed Complete Heart Block “Uncontrolled Hypothyroidism”

Background: Hypothyroidism is a common endocrine disorder with multiple system involvement and distinct clinical presentation.Its common presenting cardiovascular manifestations are sinus bradycardia and pericardial effusion usually associated with other symptoms of hypothyroidism.We report a case of a patient presenting with the uncommon manifestation of complete atrioventricular (AV) block which subsequently completely resolved with the thyroxin replacement alone suggesting hypothyroidism as the underlying aetiology.Case Presentation: A 49yr old diagnosed patient with primary hypothyroidism who was defaulted thyroxine replacement therapy presented with an attack of fainting lasted for one hour with reduced exercise tolerance, episodes of lightheadedness associated mild leg swelling and constipation for one month.On examination she had peripheral stigmata of hypothyroidism with a regular heart rate of 56 beats per minute with normal blood pressure and rest of the systemic examination.Her electrocardiogram (ECG) showed evidence of complete heart block with thyroid function tests revealing a severe hypothyroidism without any other apparent cause for AV block.The complete heart block was subsequently completely resolved with the thyroxin replacement alone without need for pacing. Conclusion:This case demonstrates an uncommon presentation of hypothyroidism with complete atrioventricular block.With prompt recognition and treatment, we were able to avoid invasive procedures and to minimize morbidity and mortality.The AV block was completely resolved with the correction of hypothyroidism.