Cardiac involvement or lyme carditis is estimated to occur in approximately 4%-10% of untreated
adults in the US that are diagnosed with acute lyme disease. Curiously, while there is a slight
predominnce of incidence of lyme disease in men, there is a 3:1 male to female preponderance for
lyme carditis.

The most common presentation consists of varying degeees of AV conduction block. Lyme carditis is
defined as acute AV conduction disturbance, usually above the bundle of his, myocarditis, or
pericarditis. Patients usually complain of dizziness, palpitations, shortness of breath and substernal
chest pain.

Accurate diagnosis of lyme carditis is challenging and requires integration of physical examination
findings, lab data and reported symptoms. AVB may be the first and only sign of lyme disease. ELISA
testing is preferred for early diagnosis, but most patients are seropositive for IgG antibody only after
several weeks.
Lyme carditis can be diagnosed accurately with historical evidence of borreliosis, presence of
erythema migrans and characteristic ECG ad cardiac MRI findings. As for serological data, serum
lyme immunoglobulin G (IgG) and IgM antibodies, positively identify in 40-60% of the patients in the
first few weeks of infection

-ECG findings include varying degrees of AVB and T wave flattening or inversions in the lateral and
inferior leads Lyme carditis that usually occurs within 3 weeks after the onset of erythma migrans
-MRI and echo show a reduced LVEF of 42% and 35% respectively, which is typical for lyme carditis;
these findings are consistent with the septal and anterior wall edema seein in myocardial
inflammation. The small focus of delayed enhancement and high T2 signal intensity in the
myocardium on MRI has recently been reported to coincide with local myocarditis in patients affected
with Lyme carditis.

Progression to complete AV block, QT interval prolongation, tachyarrhythmias, and potentially,
asystole, are associated with an initial presentation of first-degree AV block with a PR interval > 0.3
seconds. Patients who initially present with first-degree AV block may unexpectedly progress to
second-degree or complete heart block within minutes. Some patients also show escape rhythms,
brief asystole, and fluctuating bundle branch block with transient His-Purkinje involvement.
AV block with LV dysfunction frequently resolves over the course of 1-6 weeks, perhaps after
underlying myocardium inflammation resolves. PR interval gradually decreases while the myocardium
is healing and so does the grade of AV block.

Current recommendations dictate that hospitalized patients with AV block be treated with a parenteral
antibiotic, such as ceftriaxone 2 G per day for at least 48 hours, followed by doxycycline 100 mg twice
a day, for up to 21 days.
Patients who develop 3rd degree AVB, as observed in approximately 50% of patients with lyme
carditis, may ultimately need a temporary pacemaker.
While management of LV dysfunction recommends the use of beta-blockers, these agents are not
recommended in lyme carditis as they might exacerbate the degree of AV dysfunction.
Patients who had high degree AVB are discharged with a holter moniter to observe the occurence of
other episodes of high degree AVB or wenckebach, especially at night and with increased vagal tone
and intermittent changes in P wave morphology

-Cox J, Krajden M. Cardiovascular manifestations of Lyme disease. Am Heart J. 1991;122:1449-1455.
-Steere AC, Batsford WP, Weinberg M, et al. Lyme carditis: cardiac abnormalities of Lyme disease.
Ann Intern Med. 1980;93:8-16.
-Sigal LH. Early disseminated Lyme disease: cardiac manifestations. Am J Med. 1995;98(Suppl
-EUCALB 1997-2005. European Union Concerted Action on Lyme Borreliosis. Available at:
Lyme Carditis