# Acute lymphocytic myocarditis characterized by cardiogenic shock and conduction system abnormalities in patients with Hashimoto’s thyroiditis: a case report and review of literature

## TL;DR

A patient with Hashimoto’s thyroiditis developed severe heart inflammation and conduction issues, which improved with treatment including corticosteroids and vasopressors.

## Contribution

This case report highlights the rare but severe association between Hashimoto’s thyroiditis and lymphocytic acute myocarditis with cardiogenic shock.

## Key findings

- The patient showed improvement in hemodynamic stability and normalization of heart function after treatment.
- Autoimmune features like Hashimoto’s thyroiditis are linked to worse outcomes in lymphocytic myocarditis.
- Electrocardiogram findings improved over time, including resolution of AV block and partial RBBB improvement.

## Abstract

Acute myocarditis (AM) is an inflammatory heart disease that may occur as a consequence of autoimmune disorders. Although the correlation between myocarditis and hyperthyroidism has been reported in the literature, the association with hypothyroidism is less frequent.

We describe a characteristic case of lymphocytic acute myocarditis deteriorated into cardiogenic shock due to Hashimoto’s thyroiditis treated with vasopressor and inotropic drugs in combination with corticosteroid. On admission, electrocardiography revealed a sinus tachycardia with 1st degree atrioventricular (AV) block, right bundle branch block (RBBB), and left anterior fascicular block. Laboratory tests demonstrated a severe hypothyroidism and high-titre serum of antibodies against thyroglobulin. She presented a favourable clinical course, restoring haemodynamic stability. A resolution of hypothyroidism and a progressive reduction of the value of antibodies against thyroglobulin occurred. On Day 35, the patient was discharged showing on electrocardiogram the occurrence of left posterior fascicular block, disappearance of 1st degree AV block and partial improvement of RBBB along with the normalization of the left ventricular contractility abnormalities on echocardiography.

Autoimmune features, mostly Hashimoto’s thyroiditis, are associated in lymphocytic acute myocarditis to a worse prognosis and an increased risk of recurrence. More studies are needed to elucidate the underlying mechanism.