[Lyme carditis].
Untreated Lyme disease can affect the heart in up to 10% of patients. Its clinical outcome and severity vary, ranging from asymptomatic minor conduction disturbances to potentially fatal arrhythmias and severe heart failure. A history of a tick bite or a typical previous skin lesion (Erythema migrans) may be absent; clinicians should therefore keep a low threshold of suspicion when facing cardiac manifestations in a patient potentially exposed to the disease in endemic areas. We report the case of a patient with Lyme carditis expressed by variable degrees of atrio-ventricular block and review the literature.