Complete AV block in Lyme carditis: an important differential diagnosis

Lyme disease is a tick-borne spirochetal infection that may affect the heart. Cardiac manifestations include conduction disturbances and other pathologies of the heart. We report on a 37-year old male, who was admitted to the emergency department because of dizziness and generalized tiredness. Physical examination and the initial laboratory values revealed no abnormalities. The patient's electrocardiogram on admission revealed newly diagnosed bradycardia due to atrioventricular heart block. The ventricular heart rate was 35/min. The patient was admitted to the ICU. Lyme serology and Western blot were positive for Borrelia antibodies. After institution of antibiotic therapy with ceftriaxone, atrioventricular heart block resolved rapidly. We therefore have to assume that in this patient Lyme carditis was the cause of third-degree AV block.