Lyme Carditis in the Fast Lane: From Alternating Bundle Branch Block to Asystole in 12 Hours.

Lyme borreliosis is a multisystem infectious disease with well-known cardiac involvement, including potential carditis as well as conduction abnormalities. We report a case of Lyme disease in a previously healthy 24-year-old male presenting with alternating right- and left-bundle branch block, indicating infra-Hisian atrioventricular (infra-His) block with an accelerated fascicular escape rhythm. Inless than 12 hours, the conduction abnormalities progressed to asystole requiring the urgent placement of a temporary transvenous pacemaker. Subsequently, with appropriate antibiotic treatment, the patient's conduction abnormalities resolved in a week without the need for a permanent pacemaker.