Can Lyme Disease Cause Heart Block in Young Adults?
TOO YOUNG FOR HEART PROBLEMS?
LYME CARDITIS MAY BE MISSED
“They said it was anxiety—but his heart rate kept dropping.”
Heart rhythm problems in young, otherwise healthy adults are often unexpected.
But in some cases, the cause is not anxiety or stress—it’s Lyme disease affecting the heart.
Quick Answer: Lyme carditis can cause heart block in young adults and is sometimes mistaken for anxiety or stress.
Clinical Insight: When unexplained heart rhythm abnormalities occur—especially in endemic areas—Lyme disease should be considered early.
Lyme carditis occurs when Borrelia burgdorferi affects the heart’s electrical system, leading to conduction abnormalities such as atrioventricular (AV) block.
When Lyme carditis is overlooked
If untreated, Lyme disease can spread to the heart during early disseminated infection.
This condition, known as Lyme carditis, may cause:
- First-, second-, or third-degree heart block
- Palpitations
- Dizziness or lightheadedness
- Chest discomfort
- Fainting or near-fainting episodes
However, recognition depends on clinical suspicion—and Lyme disease is often not considered in younger patients.
Instead, symptoms may be attributed to anxiety, dehydration, or stress.
The SILC score: identifying Lyme carditis
The Suspicious Index in Lyme Carditis (SILC) score is a clinical tool designed to help identify patients at risk.
The scoring system includes factors such as:
- Age under 50
- Outdoor activity or tick exposure
- Residence in a Lyme-endemic area
- History of erythema migrans rash
- Constitutional symptoms
A higher score increases the likelihood that heart block is caused by Lyme disease rather than another condition.
A case of heart block in a young adult
A 20-year-old camp counselor in Wisconsin presented with heart block.
He was otherwise healthy, making the diagnosis unexpected.
Using the SILC score, he received 9 out of 10 points—strongly supporting Lyme carditis as the cause.
This case highlights how structured tools can help prevent misdiagnosis.
Why early recognition matters
Lyme carditis can progress rapidly.
Without recognition, patients may require temporary or even permanent pacemakers.
However, when treated appropriately with antibiotics, heart block due to Lyme disease is often reversible.
How common is Lyme carditis?
Lyme carditis is reported in approximately 1% of Lyme disease cases.
Although considered uncommon, its consequences can be serious—making early recognition critical.
Clinical takeaway
Heart block in a young adult should not be dismissed as anxiety without careful evaluation.
In endemic areas, Lyme disease should remain in the differential diagnosis.
Early recognition of Lyme carditis can prevent unnecessary interventions and improve outcomes.
Frequently Asked Questions
Can Lyme disease cause heart block?
Yes. Lyme carditis can disrupt the heart’s electrical system and lead to atrioventricular block.
Is Lyme carditis reversible?
Often yes. With appropriate antibiotic treatment, heart rhythm abnormalities can improve.
What is the SILC score?
A clinical tool used to assess the likelihood that heart block is caused by Lyme disease.
Why is Lyme carditis often missed?
Because symptoms may be attributed to anxiety or because Lyme disease is not considered in younger patients.
Related Reading
- Lyme Carditis Symptoms
- Lyme Disease and Atrial Fibrillation
- Heart Palpitations in Lyme Disease
- Autonomic Dysfunction in Lyme Disease
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
Hi Dr.Cameron- I wAs a patient of yours bk in 2008-12. I was diagnosed late stage.
You worked with me bk Forth from saratoga to mt kisco. You did start my journey bk to life’. Took a few years, with your help- 75% of The fatigue, heart issue, Neuropathy, joints, sensory overload, etc… did seem to disappear. I can have severe moments of brain fog, short term memory. I did see a neuropthamologist bk then. My eyes did play tricks. This did subside. But- did seem to come & go. Over the years I wrote it off as normal aging. Until this past year- my vision does change often. Blurry, far sighted, near sighted & can randomly not see at night. Seem to be progressing too fast. With covid- I put appt off until this month. I just read your article about lyme & eye issues. Is there a certain test or tests I should ask for in regards to confirming if this is lyme related? Any insight would be appreciated. I will always be grateful for the time, & expertise You & your staff gave me. You did assist in bringing me bk to life. Thank you for never giving up on lyme & having a voice.
I am glad you improved. It is still frustrating to have continued symptoms. I do not have any specific test for your eyes that I am aware of. Call my office at 914 666 4665 if you have any questions.
Hi! I read this as a person diagnosed a couple of years ago with a first degree heart block. Previously, I was treated with a PICC line and penicillin pump for a 28 day cycle for Neuro Lyme. That original Lyme had gone untreated for at least 10 years as my GP poo-poo’d Lyme results and ignored my complaints.
I have borderline deafness that no one can explain, and this first degree heart block. I’m suspicious that both may be from the Lyme infection.
As for the heart block, I was given a stress test, monitored for a month, told it’s normal for bp to get down to 30 on occasion (I am NOT an athlete) and sent home.
I’m feeling a bit nervous, and wondering if this could all be down to the Lyme, and what else could be lying in wait for me. I’m 53 and was diagnosed with the Neuro Lyme in 2016, 1st degree heart block found in 2020.
I always advise my patients to again include a doctor experienced in treating Lyme disease. Some of them have cardiac and Lyme disease issues as both are common.
Interesting article and important issue. It is particularly important that the authors remark that treatment was started because of the ‘suspicion’ of Lyme carditis. Waiting for confirmatory lab testing, especially if the testing is negative or equivocal, can be disastrous. Also glad that they investigated for cardiac dysfunction in addition to the heartblock. Although perhaps not the most common manifestation of heart involvement in Lyme it does occur. They talk about the specificity of serology, but omit discussion of the sensitivity. I would hope that they would have continued ceftriaxone based on clinical presentation and course while they evaluated for other etiologies, though their writing suggests that would not be the expected course of action; perhaps an important take away thought. The SILC scoring can indeed be useful as a way of codifying a useful and practical approach one might use regardless of familiarity with Lyme disease and its manifestations! Thanks for this interesting post. And for all you do all the time!