Lyme disease is a multisystem illness caused by Borrelia burgdorferi, a spirochete transmitted by ticks of the genus Ixodes. In the US, Lyme disease is endemic in the Northeast, Midwest, and some central areas, with hundreds of thousands of cases reported annually.1,2 Lyme carditis (LC) is uncommon, seen in <1% of all cases.2,3 We present a case of LC with an atypical presentation of atrial flutter, prolonged sinus pauses, and high-degree atrioventricular block (AVB), which ultimately required permanent pacemaker (PPM) implantation.
Case Report
A 54-year-old man with no significant past medical history presented to the emergency department with several days of malaise and progressive lower extremity rash. He denied palpitations, chest pain, shortness of breath, or syncope. His history was notable for frequent deer-hunting trips to the Central US. Physical examination revealed erythema migrans on his legs, abdomen, and back (Figures 1A and 1B). A puncture wound was noted between the first and second toes of the right foot, suggesting a tick bite (Figures 1B and 1C).
An ECG demonstrated atrial flutter with AVB. Transthoracic echocardiography was unremarkable, with preserved left ventricular ejection fraction, no diastolic dysfunction, and no significant valvular issues. Given the patient’s presentation and high clinical suspicion of Lyme disease, he was started on IV ceftriaxone 2 g daily, with continuous telemetry monitoring. Telemetry demonstrated atrial flutter with variable atrioventricular conduction, with numerous sinus pauses, lasting up to 7 seconds (Figures 1D–1I ). Subsequent Western blot testing for IgM and IgG antibodies to B. burgdorferi was positive, confirming a diagnosis of disseminated Lyme disease.
Despite IV ceftriaxone, the patient continued to demonstrate prolonged sinus pauses and high-grade AVB. Given these high-risk ECG features, a modified temporary transvenous pacemaker with active fixation leads was placed on day 5 of admission. However, at 14 days, despite IV ceftriaxone, the AVB persisted, and a PPM was implanted. The procedure was uneventful.
The patient was then transitioned to oral cefuroxime 500 mg twice daily for another 7 days, completing a 21-day regimen. At 1-month follow-up, he had made a complete recovery, with resolution of skin findings. Device interrogation revealed appropriate PPM function without further symptomatic bradyarrhythmias.
Discussion
This case highlights the broad spectrum of rhythm disturbances in LC. It underscores the need for early recognition and individualized decisions regarding PPM placement when LC-related bradyarrhythmias do not respond to appropriate antibiotics.
LC, which results from the direct invasion of the heart by spirochetes and the resultant host inflammatory response, is an early manifestation of disseminated Lyme disease. AVB is the most common presentation, seen in up to 90% of cases of LC, and is characteristically fluctuant, with potential for rapid progression from first- to third-degree AVB. High-degree AVB is seen in approximately two-thirds of such patients.3 Atrial flutter and sinus pauses are less frequently reported, and their coexistence with AVB in our patient possibly suggests diffuse involvement of the conduction system.4,5
Most cases of LC-related AVB resolve in a stepwise manner with antibiotics and do not recur. Thus, unlike other causes of high-grade AVB, patients with high suspicion of Lyme disease should be given empiric antibiotics while serologic testing is awaited.3 The Suspicious Index in Lyme Carditis (SILC) score is a useful tool to assess the likelihood of LC causing high-degree AVB, with scores of 7–12 considered high risk.6 Our patient’s SILC score was 11 of a possible 12 (2 points for constitutional symptoms, 3 points for tick bite, 4 points for erythema migrans, and 1 point each for outdoor activities and being male), prompting empiric IV ceftriaxone.1,3 Following 10–14 days of IV ceftriaxone, by which point conduction defects are expected to improve, patients may be transitioned to oral doxycycline, cefuroxime, or amoxicillin for a total antibiotic duration of 14–21 days.3
Temporary pacing is occasionally required for symptomatic bradycardia or, as in our patient, high-risk ECG features, such as alternating bundle branch block or long sinus pauses.3 PPM implantation is reserved for patients who fail to demonstrate 1:1 AV conduction after 14 days of IV antibiotics.3 Overall, PPM requirement for LC is uncommon, and even reported figures may be inflated by misdiagnosed or inadequately treated LC.7 Our patient’s atrial flutter, high-grade AVB, and long sinus pauses necessitated temporary pacemaker implantation, but given his lack of recovery of 1:1 conduction after adequate IV antibiotics, PPM implantation was necessary.
Importantly, PPM may not necessarily be lifelong; if subsequent interrogation shows no ventricular pacing requirement and treadmill stress testing demonstrates appropriate chronotropic competence, device explantation can be considered.8
Conclusion
Given the endemicity of Lyme disease in the US, clinicians must consider LC in their differential diagnoses, even in patients with atypical conduction disturbances. Although most cases of LC resolve with antibiotics alone, our case illustrates that some patients with LC ultimately require PPM implantation, underscoring the importance of vigilant monitoring and individualized management.