Without Further Delay: Lyme Carditis

Third-Degree Atrioventricular Block as the Initial Presentation of Lyme Disease

“…The score assigns weights to risk factors, namely constitutional symptoms (fever, malaise, arthralgia, and dyspnea), outdoor activity/endemic area, male gender, tick bite, age <50 years, and presence of erythema migrans. The final summed score classifies patients to be low risk (0-2), intermediate-risk (3)(4)(5)(6), or high risk (7)(8)(9)(10)(11)(12). The implementation of this risk stratification tool helps prompt recognition of LC in patients with high-degree AV block.…”

“…Treatment for LC helps shorten the overall duration of cardiac irregularities and prevent further complications of LD. Patients who have symptomatic second-or third-degree AV block or prolonged PR interval of ≥300 milliseconds are typically hospitalized and treated with intravenous antibiotics, preferably ceftriaxone [9]. Intravenous antibiotics are usually continued until the high-grade AV block has resolved, and the PR interval has become less than 300 milliseconds.…”

Lyme carditis with isolated left bundle branch block and myocarditis successfully treated with oral doxycycline

“…He also had myocarditis as evidenced from EKG changes and a markedly decreased ejection fraction for his age. Intravenous antimicrobial therapy is often used for cardiac manifestation of Lyme disease [ 5 , 11 , 12 ]. We believe this to be the first reported case of Lyme carditis with isolated LBBB and myocarditis successfully treated with oral doxycycline.…”

Systematic Approach to the Diagnosis and Treatment of Lyme Carditis and High-Degree Atrioventricular Block

“…[10,11] The pathophysiology of AV node involvement in LC may be explained by its anatomical location, histology, and metabolic mechanisms. [12] The block is often above the bundle of His at the AV node level. [4] Patients with a PR interval >300 milliseconds are at the highest risk for progression to complete AV block.…”

“…However, the AV block in LC may revert back to normal conduction, and usually resolves within the first 10 days of antibiotic administration. [12,16,17] If the AV block in LC is indeed transient, then a permanent pacemaker is not indicated. [16] Therefore, the identification of LC in patients with a high-degree AV block is imperative to prevent the inherent risks of pacemaker implantation, such as periprocedural infections, lead dislodgement, and erosions.…”