Putting Heart Block Back in the "Lyme Light".

We report a case of syncope in a young patient who presented with high-degree, variable atrioventricular heart block. Despite having no other classic manifestations of Lyme disease, she was treated with intravenous ceftriaxone for Lyme carditis on high clinical suspicion due to geographic location. The heart block resolved within 24 h of treatment. Although rare, we demonstrate the importance of considering Lyme carditis in patients who present with new-onset heart block and a history of living in an endemic area. Initiation of empiric antibiotic therapy can lead to rapid resolution of this condition. <Learning objective: Although uncommon, Lyme carditis may present without any other classic signs or symptoms of Lyme disease. It should be considered in any patient who presents with new-onset atrioventricular heart block and a history of living in an endemic area. Prompt initiation of empiric antibiotic therapy can be both diagnostic and therapeutic.>.