[Complete heart block and Lyme disease: report of two different cases and literature review].

The most typical manifestation of cardiac involvement in Lyme disease (LD) is a high grade and usually fluctuating heart block, which is generally reversible, even self-limiting. Two cases of LD with a different course of complete heart block (CHB) are described. In a 43-year-old man admitted due to episodes of syncope, the diagnosis of LD was delayed -- after pacemaker implantation -- when he developed joint and neurological symptoms. Following ceftriaxone treatment atrioventricular conduction returned to normal. In the second case of a 26-year-old woman, presenting on admission with fatigue and flu-like symptoms, ECG showed CHB with a stable escape rhythm of about 52/min. Unlike the first case, she could recall neither a tick bite nor skin rash, but epidemiological history and serologic test results were indicative of LD. In this case, antibiotic therapy did not influence atrioventricular block, which was well tolerated. This suggested the coexistence of borreliosis and previously unrecognised congenital CHB.