Lyme Carditis ECG Findings and Symptoms
Lyme carditis can affect the heart’s electrical system
ECG findings may include AV block, bradycardia, and rhythm changes
Early recognition may prevent serious complications
Lyme carditis ECG findings can include more than the classic atrioventricular (AV) block. In some patients, Lyme disease may affect cardiac conduction and lead to chest tightness, dizziness, shortness of breath, palpitations, an unusually slow heart rate (bradycardia), or abnormal rhythm findings on an electrocardiogram (ECG or EKG).
“[Lyme carditis] is caused by direct invasion of myocardial tissue by spirochetes and an immunological host response causing lymphocyte inflammation,” writes Marcos in a discussion of Lyme carditis diagnosis.1 Furthermore, “B. burgdorferi has a predisposition to cause inflammation of the atrioventricular (AV) node resulting in variable conduction abnormalities.”
These findings are important because patients with Lyme carditis may present with nonspecific symptoms, and an ECG may provide an early clue to cardiac involvement. For patients with unexplained chest symptoms, palpitations, dizziness, syncope, bradycardia, or AV block in a Lyme-endemic area, clinicians may need to consider Lyme disease symptoms as part of the differential diagnosis.
Lyme carditis symptoms in the Marcos study
The 18 patients with possible Lyme carditis were predominantly Caucasian males with a mean age of 44.5 years, with ages ranging from 24 to 79.
All of the patients met the CDC surveillance case definition for Lyme disease. One patient had an erythema migrans (EM) rash with negative blood tests.
The remaining 17 individuals had 2 to 3 IgM-specific bands for Lyme disease. Of these, 5 presented with an EM rash and 11 had 5 or more IgG bands, explains Marcos.
“The most common symptoms at presentation were chest tightness, dizziness, and dyspnea on exertion and symptoms had been present for 4-30 days,” writes Marcos.
Most patients had symptoms for several days before seeking medical attention, highlighting how Lyme carditis may initially resemble many other cardiac conditions.
Common ECG findings in Lyme carditis
The 18 patients exhibited a wide range of abnormal ECG findings.
| ECG finding | Reported abnormality |
|---|---|
| Atrioventricular (AV) block | 4 patients (1st- and 2nd-degree AV block) |
| Right bundle branch block | 6 patients |
| Atrial fibrillation | 2 patients |
| T-wave inversion | 3 patients |
| Sinus bradycardia with ST elevation | 1 patient |
| Prolonged QT interval | 2 patients |
Although atrioventricular block remains the classic ECG finding in Lyme carditis, this study suggests clinicians should also consider Lyme disease in patients from endemic areas who present with new right bundle branch block, atrial fibrillation, sinus bradycardia, prolonged QT interval, ST-T wave changes, or other unexplained conduction abnormalities.
Does Lyme carditis show up on an ECG?
An electrocardiogram, also called an ECG or EKG, is one of the most important tests used when Lyme carditis is suspected. The most common finding is atrioventricular block, but Lyme carditis may also be associated with bundle branch block, QT prolongation, ST-T wave changes, atrial fibrillation, sinus bradycardia, or rapidly changing conduction abnormalities.
In a multicenter pediatric study, Neville and colleagues found that ECG evidence of carditis, especially AV block, was associated with a diagnosis of Lyme disease.2 Among 546 children who had an ECG obtained during Lyme disease evaluation, 214 had Lyme disease. Overall, 42 children had ECG evidence of carditis, including 24 with AV block. Only 21 of the 42 children with ECG evidence of carditis had cardiac symptoms.
These findings suggest that ECG abnormalities may help support the initial diagnosis and guide management while Lyme disease testing is pending, particularly when the clinical picture raises concern for Lyme carditis.
ECG findings may vary by clinical presentation
Not every patient with Lyme disease requires an ECG. A 2024 pediatric study by Hammett and colleagues examined children with Lyme arthritis and found that ECG abnormalities were uncommon in asymptomatic patients.3
In that study, 233 children were diagnosed with Lyme arthritis, and 90 had ECGs completed. Five patients (5.6%) had ECG abnormalities: 3 had first-degree AV block, 1 had QTc prolongation, and 1 had ST-T wave changes. None had clinically significant cardiac disease.
The authors concluded that their findings did not support routine ECG screening in asymptomatic pediatric patients with Lyme arthritis. This distinction is important: ECG testing may be useful when Lyme carditis is suspected, but routine screening may not be necessary in every asymptomatic child with Lyme arthritis.
How is Lyme carditis diagnosed?
Lyme carditis is diagnosed by combining the clinical picture, exposure history, ECG findings, and Lyme disease testing. A patient from a Lyme-endemic area who presents with chest pain, palpitations, shortness of breath, dizziness, fainting, unexplained bradycardia, or AV block should prompt consideration of Lyme carditis.
Diagnosis may be more challenging when the patient does not recall a tick bite or does not have an erythema migrans rash. Clinicians may also need to distinguish Lyme carditis from other causes of myocarditis, arrhythmia, conduction disease, or unexplained cardiac symptoms. When suspicion is high, treatment and cardiac monitoring may be needed while test results are pending.
Because AV block may fluctuate rapidly, serial ECGs or continuous cardiac monitoring may be appropriate when Lyme carditis is strongly suspected.
Yeung and Baranchuk emphasize the value of the surface ECG in diagnosis and management of Lyme carditis, noting that AV block can fluctuate rapidly and may progress to complete AV block if not recognized promptly.4 They also describe the Suspicious Index in Lyme Carditis (SILC) score as one tool to help clinicians risk-stratify patients with high-degree AV block.
Broader ECG abnormalities reported in Lyme carditis
Marcos and colleagues identified a growing number of Lyme carditis cases in the literature. The most common presentation involved atrioventricular conduction abnormalities.
Other reported findings included right bundle branch block, left bundle branch block, widening of the QRS complex, AV dissociation, atrial fibrillation, ventricular dysfunction, fulminant myocarditis, and cardiac arrest.
“The spectrum of ECG abnormalities in [Lyme disease] may be broader than that previously suspected,” the authors conclude. “Clinicians should be aware of these ECG abnormalities that may be a sign of [Lyme carditis] in hyperendemic areas.”
Frequently Asked Questions
What are common Lyme carditis symptoms?
Lyme carditis symptoms may include chest tightness, chest pain, palpitations, dizziness, fainting, shortness of breath, fatigue, exercise intolerance, an unusually slow heart rate (bradycardia), or other rhythm disturbances. Some patients may have few cardiac symptoms despite abnormal ECG findings.
Does Lyme carditis show up on an ECG?
Yes. Lyme carditis may show up on an ECG (or EKG) as AV block, bradycardia, bundle branch block, atrial fibrillation, QT prolongation, ST-T wave changes, or other conduction abnormalities. AV block is the classic finding, but it is not the only possible ECG abnormality.
Can Lyme disease cause heart block?
Yes. Lyme disease can cause inflammation involving the heart’s conduction system, especially the AV node. This may result in first-degree, second-degree, or third-degree AV block. Higher-degree AV block may require hospitalization and continuous cardiac monitoring.
Can Lyme carditis cause an irregular heartbeat?
Lyme carditis can be associated with irregular heartbeat or rhythm abnormalities. Reported ECG findings include atrial fibrillation, bradycardia, bundle branch block, prolonged QT interval, and fluctuating AV conduction abnormalities.
How is Lyme carditis diagnosed?
Lyme carditis is diagnosed using the patient’s symptoms, exposure history, ECG findings, and Lyme disease testing. Clinicians should consider Lyme carditis in patients from endemic areas who develop unexplained AV block, bradycardia, palpitations, chest symptoms, dizziness, syncope, or an unexpectedly slow heart rate.
Clinical Takeaway
Lyme carditis ECG findings may extend beyond classic AV block. Patients may present with chest tightness, dizziness, shortness of breath, palpitations, bradycardia, atrial fibrillation, bundle branch block, QT prolongation, ST-T wave changes, or other conduction abnormalities.
ECG testing can be an important part of the diagnostic evaluation when Lyme carditis is suspected, especially in patients from endemic areas with unexplained conduction abnormalities or cardiac symptoms. However, newer pediatric data suggest routine ECG screening may not be necessary in asymptomatic children with Lyme arthritis.
Clinicians should consider Lyme carditis whenever unexplained ECG abnormalities or cardiac symptoms occur in a patient with possible Lyme disease exposure, as prompt recognition and treatment can prevent serious complications.
Related Articles
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Lyme carditis treated successfully after presenting as atrial fibrillation
Can Lyme disease affect your heart?
Neurologic Lyme disease
References
- Marcos LA, Castle PM, Smith K, Khoo T, Morley EJ, Bloom M, Fries BC. Risk factors for Lyme carditis: A case-control study. Eur J Prev Cardiol. 2019 Sep 19:2047487319876046.
- Neville DN, Alexander ME, Bennett JE, Balamuth F, Garro A, Levas MN, Thompson AD, Kharbanda AB, Lewander DP, Dart AH, Nigrovic LE; for Pedi Lyme Net. Electrocardiogram as a Lyme Disease Screening Test. J Pediatr. 2021;238:228-232.e1.
- Hammett DL, Del Grippo E, Loiselle CE, Thompson AD. Electrocardiogram Abnormalities in Children With Lyme Arthritis. Pediatr Infect Dis J. 2024;43(12):1152-1155.
- Yeung C, Al-Turki M, Baranchuk A. The Value of the Surface ECG for the Diagnosis and Management of Lyme Carditis: A Case Report. Curr Cardiol Rev. 2021;17(1):5-9.
- Scheffold N, Herkommer B, Kandolf R, May AE. Lyme Carditis—Diagnosis, Treatment and Prognosis. Dtsch Arztebl Int. 2015;112(12):202-208.
- Welsh EJ, Cohn KA, Nigrovic LE, Thompson AD, Hines EM, Lyons TW, Glatz AC, Shah SS. Electrocardiograph Abnormalities in Children With Lyme Meningitis. J Pediatric Infect Dis Soc. 2012;1(4):293-298.
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
Thank you for this important perspective. Dr. Cameron have you seen complex erratic blood pressures, with orthostatic hypertension, in your Lyme patients? It seems important to define such situations as having a neurological or cardiac basis ?
The problem is related in part to the effect of tick-borne illnesses on the autonomic nervous system. The issues are complex. There are POTS professionals that have described the complexity of these presentions. I find the problem is common in my patients.
Any information for connection between long-standing Lyme disease and extensive Aortic dissection.
I have read somewhere of Lyme interfering with collagen synthesis.
I was in the hospital a year ago. One doctor said he thought is was Lyme carditis. the cardiologist rolled his eyes at me and referred me to an elecrophysiologist. The diltiazem had my blood pressure @ 35/53 and terrible shortness of breath. I took myself off of it. He is located at Beth Israel. He wants to do a pulse field ablation for AFib. I was diagnosed with Lyme in 2020. Had your typical 3 weeks of doxy. My dentist puts me on doxy for his procedures. A small cut will lead to cellulitis. One cut on ankle and I had to go to a wound specialist. Back on doxy. I am 79 years old and I am scared to have the ablation. Infection and general anethesia frightens me. I saw what can happen with my mother and mother-in-law. I am of sound mind now and would hate to lose that. If I get an internal infection I’m doomed if no one notices it. Will this be dangerous for me? I get no explanations from anyone. My primary died in 2019 and I’ve had poor care since. Could I have a bit of advice?
Thank you for sharing this—your concerns are very understandable, especially given your past experiences and not getting clear answers.
I can’t provide individual medical advice here, but with complex issues like atrial fibrillation, possible Lyme involvement, and side effects from medications like diltiazem, it’s reasonable to ask for a clear explanation of risks and options—or seek a second opinion.
Your concerns about safety, infection, and quality of life deserve to be taken seriously.