Palpitations and dizziness prompted a previously healthy 21-year-old cable lineman from southeastern Pennsylvania to seek medical attention. An ECG showed first-degree heart block. The young man was scheduled for outpatient cardiology consultation, but his symptoms worsened and he presented to an emergency department with chest pain and fever 2 days later. Further evaluation revealed that for the past 3 weeks he had myalgia; arthralgia; fatigue; and an expanding, erythematous, nonpruritic rash on his trunk and extremities. He did not recall any tick bites.
On admission, temperature was 38.5°C (101.2°F); other vital signs were normal. Disseminated erythema migrans was noted on the arm (A), right leg (B), and trunk (C). An ECG showed complete heart block with an accelerated junctional rhythm (D). Intravenous ceftriaxone was started. Within 10 days, the heart block and symptoms resolved, and the patient was discharged. He completed 3 weeks of treatment with oral doxycycline.
Disseminated erythema migrans and carditis are manifestations of early disseminated Lyme disease. Carditis occurs in up to 8% of untreated adults. Heart block resolves with antibiotic treatment and rarely requires a pacemaker.
Lyme disease remains part of the differential diagnosis in otherwise healthy patients who present with heart block. Evaluation of such patients should prompt a thorough review of systems and physical examination to detect signs and symptoms of Borrelia burgdorferi infection, especially in areas where the infection is endemic.
Mild carditis with first-degree heart block can be treated with oral doxycycline. In this case, diagnosis of Lyme disease during the patient’s initial office visit may have prevented his hospitalization.