Cor Vasa 2019, 61(6):629-634 | DOI: 10.33678/cor.2019.040

Third degree atrioventricular block as a rare complication of Graves' thyrotoxicosis

Michal Širanec, Sudheera Magage, Martin Válek, Josef Marek, Jan Šimek, Jan Bělohlávek, Miroslav Pšenička, Aleš Linhart

2nd Department of Internal Medicine - Cardiology and Angiology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague

Complete atrioventricular (AV) block is a rare but life-threatening complication of thyrotoxicosis. In the literature, only a few cases with uncertain causal link to hyperthyroid status have been described so far. Because of the lack of data, there is no clear consensus on the reversibility of AV conduction abnormality and hence on the need for permanent pacemaker implantation. In the case report, we describe a case of a 35-year-old woman with newly diagnosed Graves' thyrotoxicosis complicated by syncope due to complete AV block. Upon admission to hospital, a spontaneous recovery of the AV conduction with 1 : 1 ratio occurred, resulting in significant sinus tachycardia with a heart rate of 150 bpm, which manifested by chest pain and pre-collapse state and led to the development of heart failure due to hyperkinetic circulation. Further complication was an asystole caused by a recurrence of complete AV block without occurrence of escape rhythm, with the need of a 2-minute cardiopulmonary resuscitation and emergency temporary transvenous pacing. After 48 hours of thyrostatic and corticosteroid treatment, the heart rhythm stabilized, with a tendency to sinus tachycardia. The further course was uncomplicated, including a good beta-blocker tolerance. A comprehensive examination (including cardiac magnetic resonance) did not show any other cause explain- ing the complete AV block. The patient refused permanent pacemaker implantation which was considered. During the next 3-month follow-up, a recurrence of AV block did not occur.

Keywords: Asystole, Graves' disease, Sinus tachycardia, Third degree atrioventricular block, Thyrotoxicosis

Accepted: February 2, 2019; Published: December 15, 2019  Show citation