# Unexpected complication following total thyroidectomy: A case report and brief review of the literature

## TL;DR

A rare case of supraventricular tachycardia following thyroidectomy in a hypothyroid patient is reported, highlighting the importance of ECG for diagnosis and treatment.

## Contribution

This case report adds to the limited literature on SVT occurrence in post-thyroidectomy hypothyroidism.

## Key findings

- SVT occurred in a hypothyroid patient after total thyroidectomy, confirmed by ECG as AVNRT.
- Successful treatment with adenosine and revised levothyroxine led to no recurrence at 2-month follow-up.
- Literature review identified four similar cases, all presenting with palpitations and managed with ECG-guided interventions.

## Abstract

Supraventricular tachycardia (SVT) involves a group of supraventricular tachyarrhythmiasfast heart rhythms originating above the ventricles. While SVT is commonly associated with hyperthyroidism, its occurrence in hypothyroidism is rare. The present case report describes a case of SVT occurring in the setting of post-thyroidectomy hypothyroidism. A 50-year-old female patient with a history of total thyroidectomy presented with palpitations and chest tightness. A 12-lead electrocardiogram (ECG) demonstrated atrioventricular nodal reentrant tachycardia (AVNRT) with a heart rate of 200 bpm. A laboratory evaluation revealed elevated thyroid-stimulating hormone levels, indicating biochemical hypothyroidism. Adenosine was administered, successfully restoring sinus rhythm. She was discharged with a revised levothyroxine regimen. At the 2-month follow-up, she remained asymptomatic, hemodynamically stable and free of recurrent arrhythmia. Ventricular and supraventricular arrhythmias, including SVT and Torsades de Pointes, are uncommon in hypothyroidism. The most common underlying mechanism is re-entry, with AVNRT being most common. In addition, the present study reviewed 4 cases of SVT following thyroidectomy reported in the literature. Palpitations were universal, and dyspnea occurred in 3 cases. In total, 2 patients were on hypothyroid treatment at the time, and similarly, 2 patients received adenosine intravenously. Myocardial structural changes, and slow cardiac repolarization lead to early after-depolarizations. A review of case reports revealed SVT occurring during hypothyroid states, particularly in women, often presenting with palpitations and diagnosed via ECG. Management relies on ECG-guided diagnosis and acute treatment with vagal maneuvers or adenosine. The identification of SVT in hypothyroidism is rare, but should be considered. ECG is key for diagnosis and management.