Workup and Treatment for Suspected Lyme Carditis
Diagnostic Workup
In patients with acute myocarditis/pericarditis of unknown cause in an appropriate epidemiologic setting (Lyme-endemic area with tick exposure), you should test for Lyme disease. 1
Clinical Presentation to Recognize
Look for these specific cardiac symptoms that warrant evaluation:
- Dyspnea, palpitations, lightheadedness, chest pain, or syncope 1
- Exercise intolerance, presyncope, or pericarditic pain 1
- Evidence of pericardial effusion or elevated cardiac biomarkers (troponin) 1
- Edema or shortness of breath 1
Electrocardiogram Strategy
Perform an ECG only in patients with signs or symptoms consistent with Lyme carditis (not as routine screening in all early Lyme disease). 1
- 90% of Lyme carditis patients develop cardiac conduction abnormalities, most commonly atrioventricular (AV) block 2
- 60% develop signs of perimyocarditis 2
- AV block can range from first-degree to complete heart block, junctional rhythm, or asystolic pauses 3
- Less commonly, sinus bradycardia without conduction defects may occur 4
Serologic Testing
- Borrelia serology (ELISA) with confirmatory Western blot is the diagnostic standard 2
- Important caveat: Serology may be negative in the very early phase but is always positive in later phases 2
- In the absence of concomitant erythema migrans, serologic confirmation is necessary 5
Additional Diagnostic Studies
- Cardiac MRI can confirm the diagnosis and monitor subsequent course 2
- Cardiac biomarkers (troponin) may be elevated 1
Treatment Algorithm
Step 1: Determine Need for Hospitalization
Admit patients with continuous ECG monitoring if they have: 1
- PR interval >300 milliseconds
- Other arrhythmias beyond first-degree AV block
- Clinical manifestations of myopericarditis (pericarditic pain, effusion, elevated troponin)
Step 2: Antibiotic Selection Based on Setting
For Hospitalized Patients:
Start IV ceftriaxone initially, then switch to oral antibiotics once clinical improvement occurs. 1
For Outpatients:
Use oral antibiotics (oral preferred over IV for stable outpatients). 1
Oral antibiotic options include: 1
- Doxycycline
- Amoxicillin
- Cefuroxime axetil
- Azithromycin
Step 3: Duration of Therapy
Treat for 14-21 days total (not longer durations). 1, 5
Management of Bradycardia/Heart Block
For symptomatic bradycardia that cannot be managed medically, use temporary pacing modalities rather than implanting a permanent pacemaker. 1
- Cardiac conduction disturbances are usually reversible with antibiotic therapy 2, 3
- Temporary cardiac pacing combined with antibiotics successfully manages AV block until resolution 6
- Permanent pacemaker implantation is only exceptionally necessary 2
Critical Pitfalls to Avoid
Do not routinely test for Lyme disease in patients with chronic cardiomyopathy of unknown cause (testing is for acute presentations only). 1
Do not implant permanent pacemakers prematurely - the conduction abnormalities typically resolve with antibiotic treatment, making permanent pacing unnecessary in most cases. 1, 2
Maintain high clinical suspicion in endemic areas - Lyme carditis can present without classical erythema migrans or other typical Lyme disease features, particularly in young patients with unexplained bradycardia or AV block. 6, 4
Close follow-up is essential for patients who developed high-degree AV block to monitor for any late sequelae. 6
Prognosis
When treated according to current guidelines, Lyme carditis has a highly favorable prognosis. 2 There is no clear evidence for an association between borreliosis and later development of dilated cardiomyopathy. 2