Cardiovascular Impact of Lyme Disease
Lyme carditis occurs in 4-10% of Lyme disease cases and most commonly presents as atrioventricular conduction block, which is typically reversible with antibiotic therapy and does not require permanent pacing. 1, 2
Clinical Manifestations
Cardiac involvement typically develops within 2 months of initial infection, often within 21 days of tick exposure. 1 The cardiovascular manifestations include:
Conduction Abnormalities
- 90% of Lyme carditis patients develop cardiac conduction abnormalities, with atrioventricular block being the cardinal manifestation 2, 3
- Two-thirds of patients progress to complete heart block, and the degree of AV block can fluctuate rapidly 4
- Heart block occurs at the level of the AV node and is often unresponsive to atropine 3
Myopericardial Involvement
- 60% develop signs of perimyocarditis 2
- Pericardial effusion may occur, though severe or fulminant congestive heart failure is not typical 1
- Elevated cardiac biomarkers such as troponin may be present 5, 6
Presenting Symptoms
Patients may present with: 5, 6
- Dyspnea, palpitations, lightheadedness
- Chest pain (including pericarditic pain)
- Syncope or presyncope
- Exercise intolerance
- Edema
Diagnostic Approach
When to Suspect Lyme Carditis
Perform ECG only in patients with signs or symptoms consistent with Lyme carditis (not as routine screening). 5
In patients with acute myocarditis/pericarditis of unknown cause in an appropriate epidemiologic setting, testing for Lyme disease is strongly recommended. 5, 6
Diagnostic Testing
- Borrelia serology (ELISA) may be negative in early phase but is always positive in later phases 2
- In the absence of concomitant erythema migrans, serologic confirmation is necessary 1, 6
- Cardiac MRI can confirm diagnosis and monitor subsequent course 2
Critical Pitfall
Do not routinely test for Lyme disease in patients with chronic cardiomyopathy of unknown cause, as the association is unclear and false-positive rates are significant. 5, 6, 3
Treatment Algorithm
Risk Stratification and Monitoring
Patients with significant PR prolongation (>300 milliseconds), other arrhythmias, or clinical manifestations of myopericarditis require hospital admission with continuous ECG monitoring. 5 This is a strong recommendation despite very low-quality evidence, reflecting the potential for rapid deterioration. 5
Continuous heart rhythm monitoring is essential because the degree of AV block can fluctuate rapidly. 4
Antibiotic Therapy
Hospitalized Patients
Initially use IV ceftriaxone until clinical improvement occurs, then switch to oral antibiotics to complete treatment. 5, 6 This approach balances the severity of presentation with the goal of minimizing IV therapy duration.
Outpatient Management
For outpatients with Lyme carditis, oral antibiotics are preferred over IV antibiotics. 5, 6
Oral antibiotic options include: 5, 6
- Doxycycline
- Amoxicillin
- Cefuroxime axetil
- Azithromycin
Duration
Treat for 14-21 days total, not longer durations. 5, 6 This recommendation applies regardless of initial route of administration.
Pacing Management
For symptomatic bradycardia that cannot be managed medically, use temporary pacing modalities rather than implanting a permanent pacemaker. 5, 6 This is a strong recommendation based on moderate-quality evidence, reflecting the typically reversible nature of conduction abnormalities. 5
Temporary pacing may be necessary in more than 30% of patients, but permanent heart block rarely develops. 3 Routine permanent pacemaker implantation is contraindicated because cardiac conduction disturbances are usually reversible with antibiotic treatment. 6, 4
Prognosis
When treated according to current guidelines, the prognosis is highly favorable. 2 Most patients recover completely, with cardiac conduction abnormalities typically resolving with antibiotic therapy. 2 The clinical course is usually benign, though rare deaths from Lyme carditis have been reported. 3
The frequency of Lyme carditis appears to be lower in recent studies, possibly due to earlier recognition and treatment of erythema migrans. 1