Lyme Carditis
Lyme disease is caused by the spirochete Borrelia burgdorferi, transmitted by the Ixodes tick. Mostly in 2 regions:
Northeast (Mid-Atlantic and New England states), and
North Central (Wisconsin and Minnesota)
This pearl will focus specifically on lyme carditis and not other clinical manifestations of lyme.
3 phases of the disease:
1) early localized
2) early disseminated
3) late
Lyme carditis occurs in 1% of patients with lyme and during the early disseminated phase. This is typically 1-2 months after infection.
Symptoms
lightheadedness
syncope
shortness of breath
palpitations
chest pain
What's going on?
Causes AV conduction abnormalities that can vary rapidly; so a person can go from a first degree block to complete AV nodal block within minutes! They can also revert back within minutes.
Highest risk for progression to complete block is PR > 300
Can cause a myopericarditis that is self-limited
Sudden cardiac death has been reported
Diagnosis
Need positive lyme serologies -- ELISA and confirmatory Western blot
These tests can test for IgM, but this gives higher false positives. Since lyme carditis occurs during the early disseminated phase, it is better to screen for lyme IgG
Management
Patients with PR > 300 should be hospitalized, given IV antibiotics and monitored with tele
Ceftriaxone 2g/day IV in adults (50-75mg/kg/day IV in children)
When PR becomes < 300, can switch to oral antibiotics (doxycycline 100mg BID, amoxicillin 500mg TID, or cerfuroxime 500mg BID)
Need a total of 21-28 days of antibiotic therapy
*It should be noted that chronic lyme disease has come to refer to an entirely different entity: https://www.nybooks.com/daily/2018/07/25/the-challenge-of-chronic-lyme/