Lyme Disease Heart Block: How Lyme Carditis Can Progress Rapidly
Lyme carditis can cause heart block and dangerously slow heart rates.
Conduction abnormalities may worsen within hours—or even minutes.
Early recognition and antibiotic treatment often prevent permanent pacemaker implantation.
Lyme disease heart block is one of the most important cardiac complications of Lyme disease. Although Lyme carditis is uncommon, inflammation of the heart’s electrical conduction system can lead to rapidly progressive atrioventricular (AV) block, Lyme disease bradycardia (a slow heart rate), dizziness, fainting, chest discomfort, and shortness of breath. Fortunately, prompt recognition and antibiotic treatment often result in complete recovery without the need for permanent pacing.
Although Lyme disease is best known for causing an erythema migrans rash, joint pain, and neurologic symptoms, it can also affect the heart. Cardiac involvement may present with heart block, bradycardia, myocarditis, pericarditis, or, less commonly, heart failure. Because these complications are usually reversible with appropriate antibiotics, recognizing Lyme carditis early is essential.
Lyme disease can trigger several cardiac complications, including Lyme carditis, which typically develops during the early disseminated stage of infection. “Lyme carditis is an important reversible cause of heart block, especially in endemic areas,” wrote Aljadba and colleagues in their article, Lyme Carditis Manifesting as Wenckebach Heart Block.1 “Prompt recognition of this potentially lethal condition, with appropriate initiation of antibiotics, can improve clinical outcomes and avoid unnecessary pacemaker implantation.”
Symptoms of Lyme carditis
Patients with Lyme carditis may experience a wide range of symptoms depending on the severity of the conduction abnormality. Common symptoms include:
- Chest pain or chest tightness
- Lightheadedness or dizziness
- Near-fainting (presyncope) or fainting (syncope)
- Shortness of breath
- Palpitations
- Bradycardia (slow heart rate)
- Fatigue or reduced exercise tolerance
Heart block is the most common manifestation of Lyme carditis, but patients may first notice fatigue, dizziness, chest discomfort, or an unusually slow pulse before an electrocardiogram (ECG) reveals the conduction abnormality.
Because conduction abnormalities can worsen rapidly, patients with suspected Lyme carditis often require continuous cardiac monitoring while receiving antibiotic therapy.
Can Lyme disease cause heart block?
Yes. Lyme disease can inflame the heart’s electrical conduction system, leading to first-, second-, or third-degree AV block. Although many patients initially develop only mild conduction delays, progression may occur within hours. Prompt diagnosis is essential because Lyme carditis usually responds well to antibiotics, allowing the heart’s normal conduction to recover.
How is Lyme disease heart block treated?
Treatment depends on the severity of the conduction abnormality. Patients with advanced AV block or significant symptoms are generally hospitalized for continuous cardiac monitoring and treated with intravenous ceftriaxone. Individuals with milder disease may be candidates for oral antibiotics once they are clinically stable.
Some patients require temporary cardiac pacing if severe bradycardia or complete heart block develops. However, because Lyme carditis is usually reversible, permanent pacemaker implantation can often be avoided when prompt antibiotic therapy is started.
How quickly can Lyme heart block worsen?
The following two cases illustrate how rapidly Lyme disease heart block can progress. In one patient, conduction abnormalities developed overnight. In the second, the AV block progressed from first-degree to complete heart block within hours. These cases underscore the importance of recognizing Lyme carditis early and closely monitoring affected patients.
72-year-old man develops rapidly progressive Lyme disease heart block
A 72-year-old man presented to the emergency department with left-sided chest tightness, lightheadedness, presyncope, and mild shortness of breath.
While hospitalized, his condition quickly escalated. Overnight, he developed symptomatic bradycardia, with his heart rate falling to 30–40 beats per minute.
His initial electrocardiogram (ECG) was normal, but a repeat study demonstrated “sinus bradycardia with Mobitz type 1 (Wenckebach) heart block and progressive prolonged PR interval,” the authors wrote.
A Western blot test confirmed Lyme disease, with all 10 IgG bands reactive.
The patient was treated successfully with intravenous ceftriaxone.
“Lyme carditis typically resolves with antibiotic treatment alone and cardiac intervention is often not needed.”
After seven days of IV antibiotic therapy, both the heart block and bradycardia resolved completely without the need for a temporary pacemaker.
Although AV block often begins as a mild conduction abnormality, it can progress rapidly, as demonstrated in this patient.
“[Lyme carditis] should be on the differential diagnosis and appropriate workup done when a patient presents with a heart block, especially in an endemic area.”
Lyme carditis may be the first manifestation of Lyme disease and typically develops one to two months after infection. Although uncommon, Lyme carditis may also present as myocarditis, pericarditis, endocarditis, dilated cardiomyopathy, and heart failure.
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33-year-old woman progresses to complete Lyme heart block within hours
The study, Lyme Carditis: An Interesting Trip to Third-Degree Heart Block and Back by Afari and colleagues2 demonstrates the importance of obtaining a careful travel and exposure history when evaluating patients with suspected Lyme carditis.
A 33-year-old woman presented to the emergency department during the summer with intermittent, dull chest discomfort that had persisted for three days. She also reported shortness of breath and lightheadedness.
Three weeks earlier, she had visited the emergency department with photophobia, headache, and a fever of 101.4°F.
One month before the onset of her cardiac symptoms, she had been hiking in the mountains of New Hampshire, an area where Lyme disease is endemic.
A spinal tap was negative for Lyme disease, but the patient had a 5-cm erythema migrans (EM) rash on her neck.
“An initial electrocardiogram showed a first-degree AV block,” the authors wrote. “A presumptive diagnosis of early disseminated phase of Lyme disease was made, and the patient was admitted to the cardiac telemetry floor.”
Several hours after admission, the patient’s first-degree AV block progressed to second-degree heart block and then rapidly to complete (third-degree) heart block.
Western blot testing confirmed Lyme disease. The patient had positive IgG bands (28, 30, 39, 41, 45, and 58) and positive IgM bands (39 and 41).
She was diagnosed with Lyme disease based on the presence of an erythema migrans rash together with confirmatory laboratory testing.
“As demonstrated in this case, the worsening of the degree of AV block may occur within minutes.”
After receiving three doses of intravenous ceftriaxone, the patient’s complete heart block regressed to Mobitz type I AV block and then to first-degree AV block.
One month after treatment, all cardiac symptoms had resolved completely.
According to the authors, this case highlights:
- How rapidly conduction abnormalities in Lyme carditis can fluctuate, emphasizing the importance of continuous telemetry monitoring.
- The need to consider Lyme disease in patients presenting with new AV nodal conduction disorders, particularly in endemic regions.
- The importance of obtaining a careful travel and tick exposure history.
- The value of prompt antibiotic treatment to prevent unnecessary permanent pacemaker implantation.
Frequently Asked Questions
Can Lyme disease cause heart block?
Yes. Lyme carditis can inflame the heart’s electrical conduction system, resulting in first-, second-, or third-degree AV block. Most patients recover with appropriate antibiotic treatment.
Can Lyme disease cause a slow heart rate?
Yes. Lyme disease bradycardia may occur when Lyme carditis disrupts the heart’s normal electrical conduction system. A slow heart rate accompanied by dizziness, fainting, or chest pain requires prompt medical evaluation.
Can Lyme disease heart block be reversed?
In many patients, Lyme disease heart block resolves after appropriate antibiotic therapy. Some individuals require temporary cardiac pacing while the inflammation improves, but permanent pacemakers are frequently unnecessary.
When should someone seek emergency care?
Anyone with suspected Lyme disease who develops chest pain, fainting, severe dizziness, palpitations, shortness of breath, or a very slow heart rate should seek immediate medical attention because Lyme carditis can progress rapidly.
Clinical Takeaway
Lyme disease heart block is an uncommon but potentially life-threatening manifestation of Lyme carditis. As these two cases demonstrate, conduction abnormalities can worsen dramatically over hours—or even minutes. Early recognition, continuous cardiac monitoring when appropriate, and prompt antibiotic treatment can lead to complete recovery and frequently eliminate the need for permanent pacemaker implantation.
In patients from Lyme-endemic areas who present with new heart block, bradycardia, chest pain, or unexplained cardiac symptoms, Lyme carditis should remain an important and potentially reversible diagnosis.
Related Articles
Learn more about Lyme carditis and other cardiac complications of Lyme disease:
Lyme carditis: symptoms, diagnosis, and treatment
Lyme disease symptoms: a clinical guide
Lyme carditis causes complete heart block in a 26-year-old man
Temporary pacemaker effective in acute Lyme carditis with severe heart block
References
- Aljadba I, Suresh K, Hussain KM. Lyme Carditis Manifesting as Wenckebach Heart Block. Cureus. 2021;13(11):e19251. doi:10.7759/cureus.19251.
- Afari ME, Marmoush F, Rehman MU, Gorsi U, Yammine JF. Lyme Carditis: An Interesting Trip to Third-Degree Heart Block and Back. Case Reports in Cardiology. 2016;2016:5454160.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
