Background: Lyme disease (LD) is a tick-borne systemic infectious disease caused by the spirochete Borrelia burgdorferi. Clinical manifestations are various. Approximately 2/3 of patients have disseminated form of disease such as Lyme carditis (LC), present in <1% of patients in Europe. The cardinal manifestation of LC is a self-limited conduction system disease, most frequently involving the atrioventricular node and leading to varying degrees of AV nodal block. (1-3)

Case Report: 48-year-old male without any known past medical or family history of cardiovascular disease presented with postural dizzines, presenting 2 months prior to admission. He was employed in the forest industry and reported allegedlly tick bite. Physical examination on admission did not revealed any skin rash. Initial blood work were within normal limits. EKG on admission showed second degree AV block, and RBBB. Holter EKG revealed AV conduction abnormalites; varying from second (Mobitz II) to third degree AV block. Echocardiography reveale hypokinesis of inferoposterior wall. An exercise stress test showed no signs of coronary insufficiency. Considering patients' risk of exposure to infected ticks and history of a tick bite, serological testings were performed, revealing elevated IgG levels for B.burgdorferi. After antibiotic therapy his heart block resolved.

Discussion: The diagnosis of LC is challenging: it is usually made in the presence of other manifestations and stages of LD. In differential diagnostic rethinking we considered ischemic etiology which was eventually excluded according to course of the disease and serological findings. Patients suspected of having early disseminated or late disease are diagnosed clinically and serologically. Positive serologic testing is not by itself diagnostic, nor does negative serologic testing exclude the diagnosis.There is an overall consensus in favour of antibiotic treatment but dosage and duration of treatment is still unclear.

Conclusion: The diagnosis of LC is not always obvious but may be diagnosed if there is a high degree of suspicion. Serological results should always be interpreted in the context of the patient’s clinical condition or course of the disease. This case also demostrated the importance of detailed history taking.