Lyme carditis presenting as sick sinus syndrome.

Lyme disease, a tickborne infection caused by Borrelia burgdorferi, can affect cardiac tissue causing Lyme carditis. Patients with Lyme carditis most commonly present with varying degrees of atrioventricular block and rarely with sick sinus syndrome. A previously healthy 22 year-old male presented with syncope. His 2 week Holter monitor showed sinus pauses of 6.5 and 6.8 s. Lyme serology, including Western blot, was positive. A stress test, completed after 8 days of intravenous antibiotics for Lyme carditis, revealed no conduction abnormalities. He was discharged on 3 weeks of oral antibiotics and had no conduction abnormalities on subsequent follow-up.