Lyme Carditis: Can Acute Lyme Disease Cause Complete Heart Block?
Lyme carditis may cause complete heart block and severe bradycardia.
Cardiac complications can occasionally appear early in acute Lyme disease.
Prompt recognition and antibiotic treatment may reverse conduction abnormalities.
“A suspected case of Lyme disease causing complete heart block” by Isha and colleagues described a unique case of Lyme carditis in a 21-year-old man whose cardiac symptoms emerged early in the course of illness.
According to the authors, complete heart block is generally considered a later manifestation of Lyme disease. However, this patient developed severe cardiac involvement during acute infection.
The report highlights how Lyme carditis may occasionally present earlier than expected and may initially resemble other cardiac emergencies.
Case report: complete heart block in acute Lyme disease
A 21-year-old man was admitted to the hospital after he was found unresponsive with severe bradycardia.
An electrocardiogram (ECG) revealed complete heart block with diffuse T-wave abnormalities.
The patient was treated with intravenous ceftriaxone and required temporary pacemaker support.
According to the authors, “The patient improved with antibiotic therapy and temporary pacemaker support during the initial few days of admission.”
Because the patient had recently traveled to a Lyme-endemic region two weeks before symptom onset, clinicians pursued testing for Lyme disease and other tick-borne infections.
Lyme testing was positive by IgM but negative by IgG — an uncommon finding in Lyme carditis according to the authors.
The patient also tested positive for Babesia microti.
Over the following seven days, the atrioventricular block gradually improved, and the patient was discharged with a 14-day course of oral antibiotics.
How Lyme carditis affects the heart
Lyme carditis occurs when Borrelia burgdorferi affects the heart’s electrical conduction system.
Cardiac involvement may lead to:
- Bradycardia
- Atrioventricular (AV) block
- Palpitations
- Dizziness or syncope
- Chest pain
- Shortness of breath
- Complete heart block
The severity of conduction abnormalities may fluctuate rapidly over hours or days.
Some patients recover fully with antibiotic treatment, while others may require temporary cardiac pacing during acute illness.
For broader cardiac complications, see Lyme carditis.
Why this Lyme carditis case was unusual
The authors noted several unusual features in this case.
- Cardiac manifestations appeared early in acute Lyme disease
- Lyme IgM was positive while Lyme IgG remained negative
- The patient also had positive Babesia microti testing
According to the report, Lyme carditis more commonly develops several weeks after infection rather than during the early IgM phase.
The presence of coinfection also raised questions regarding inflammatory burden and clinical severity.
For related coinfection pathways, see Babesia and Lyme disease.
Can Lyme carditis be fatal?
Yes. Although uncommon, Lyme carditis can lead to severe conduction abnormalities, syncope, cardiac instability, and sudden death if unrecognized.
Prompt diagnosis is important because many conduction abnormalities improve with antibiotic treatment and supportive cardiac care.
Clinicians may consider Lyme disease in patients presenting with unexplained AV block, bradycardia, or fluctuating conduction abnormalities — particularly in endemic regions or after tick exposure.
Frequently Asked Questions
Can Lyme disease cause complete heart block?
Yes. Lyme carditis may cause complete heart block when infection affects the heart’s electrical conduction system.
What is Lyme carditis?
Lyme carditis is a cardiac complication of Lyme disease involving inflammation and disruption of electrical conduction pathways within the heart.
Can Lyme carditis cause bradycardia?
Yes. Lyme carditis may cause significant slowing of the heart rate, including severe bradycardia and AV block.
Can Lyme carditis improve with antibiotics?
Yes. Many patients experience improvement in conduction abnormalities after appropriate antibiotic treatment.
Can Babesia occur with Lyme carditis?
Yes. Coinfections such as Babesia microti may occur alongside Lyme disease and may complicate the clinical presentation.
Clinical Takeaway
Lyme carditis may present with severe bradycardia, AV block, or complete heart block, sometimes early in the course of acute Lyme disease.
Because conduction abnormalities may fluctuate rapidly, early recognition and cardiac monitoring are important in patients with suspected Lyme carditis.
Prompt antibiotic treatment may reverse potentially life-threatening cardiac conduction abnormalities associated with Lyme disease.
Related Articles
These related articles explore Lyme carditis, coinfections, neurologic complications, and cardiovascular manifestations associated with tick-borne disease.
Lyme coinfections
Delayed Lyme disease diagnosis
Neurologic Lyme disease
Persistent Lyme disease
Lyme disease misdiagnosis
References
- Isha, et al. A suspected case of Lyme disease causing complete heart block. Cureus. 2023.
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
I have AFIb and this diagnosis makes me very nervous.
I shared the published case report to add Lyme disease as a consideration. There are so many other causes of A fib. Often there is no answer