Early-onset Lyme carditis with concurrent disseminated erythema migrans.

Background: Lyme disease is an infection that is estimated to affect over 300,000 people in the United States annually. Typically, it presents with erythema migrans (EM), an annular rash at the site of tick attachment, within 3 to 30 days of inoculation. Untreated patients may progress to early disseminated disease. A further complication, Lyme carditis is rare but may occur several weeks later. It commonly manifests as a variable atrioventricular (AV) conduction block, with a high-grade AV block occurring in only 1% of untreated patients. This case demonstrates an unusually early presentation of Lyme carditis with complete heart block.

Case Presentation: A 21-year-old male was transferred from an outside emergency department (ED) for possible pacemaker placement due to symptomatic third-degree AV block. Four days earlier the patient presented to the outside ED with fever, chills, and unrecognized EM on his right neck. He was discharged with antipyretics, but no antibiotic therapy. On the day of transfer, he returned with persistent fevers, EM now on his trunk and upper extremities, lightheadedness, and substernal chest pressure. An electrocardiogram revealed the third-degree AV block leading to transfer. Upon arrival, the patient was promptly diagnosed with Lyme carditis. Pacemaker implantation was deferred, and intravenous (IV) ceftriaxone was initiated. Within 48 hours his third-degree AV block improved to a first-degree block. By this time, his EM had also resolved. He was discharged with oral doxycycline and a 30-day event monitor, which ultimately showed persistent first-degree AV block.

Conclusions: This case reinforces a unique presentation of Lyme carditis. Disseminated EM and Lyme carditis may present concurrently within 2 weeks of tick attachment. Early recognition and treatment is important for preventing progression to disseminated infection. Lyme-associated AV block will reverse within 48 to 72 hours of initiating IV antibiotic therapy and will not require pacemaker implantation. Lyme carditis should be considered in patients without heart disease who present with any degree of AV block.