# Lyme Carditis With Complete Heart Block

## TL;DR

A 42-year-old man with Lyme carditis developed a severe heart block but improved rapidly with ceftriaxone treatment.

## Contribution

This case highlights the importance of early diagnosis and treatment of Lyme carditis to avoid serious complications.

## Key findings

- Third-degree AV block resolved within 48 hours with intravenous ceftriaxone.
- Transition from third-degree to first-degree AV block occurred after treatment initiation.
- Early recognition prevented the need for permanent pacemaker implantation.

## Abstract

Lyme disease, the most common tick-borne infection in North America, can lead to multi-organ involvement, including Lyme carditis. This report describes the case of a 42-year-old male who presented with a third-degree atrioventricular (AV) block due to Lyme carditis. The patient reported a history of a recent tick bite and erythema migrans rash, followed by progressive fatigue, palpitations, and dyspnea. Initial electrocardiogram (EKG) revealed third-degree AV block with ventricular escape rhythm, necessitating temporary transvenous pacing and intravenous ceftriaxone therapy. Within 48 hours, the patient significantly improved, transitioning to first-degree AV block with a decreasing PR interval. After clinical stabilization, intravenous ceftriaxone was switched to oral doxycycline, and the patient was discharged with outpatient follow-up. This case emphasizes the significance of early recognition and treatment of Lyme carditis to prevent life-threatening complications and avoid unnecessary permanent pacemaker implantation.