A Case of Lyme Carditis With Variable Heart Block Successfully Treated With Oral Doxycycline.

A 39-year-old male without significant past medical history presented with three weeks of worsening fatigue, migratory arthralgia, rash, and unilateral facial weakness after spending three months in Vermont. Serology showed positive Lyme titers 1:64 for both IgM and IgG. EKG on presentation showed a P-R interval of 384 ms, and the patient was admitted for concern of Lyme carditis. Serial EKGs obtained throughout his stay demonstrated variability between first- and second-degree heart blocks. After consultation with Infectious Disease, he was transitioned to oral doxycycline to complete a 21-day course. The patient's heart block and other symptoms had resolved on follow-up after the treatment course had been completed.