Lyme Carditis and Atrial Fibrillation: A Missed Presentation
It can begin with atrial fibrillation.
And that can delay diagnosis.
Lyme carditis atrial fibrillation is an uncommon presentation that can lead to missed or delayed diagnosis.
In a BMJ case report, a 23-year-old man presented with sudden palpitations and was found to have atrial fibrillation (AF) with a mildly dilated left atrium.
The patient did not recall a tick bite or rash.
Although Lyme carditis was included in the differential diagnosis, it was considered unlikely because the initial rhythm was atrial fibrillation rather than the more typical atrioventricular (AV) block.
Initial Improvement—Then Rapid Deterioration
The patient was treated with metoprolol and discharged after his heart rhythm spontaneously returned to normal sinus rhythm.
However, just four days later, he returned with worsening symptoms.
Repeat evaluation revealed:
- Mobitz II AV block
- Intermittent complete heart block
Clinical pattern: Lyme carditis can evolve rapidly from mild arrhythmia to high-grade conduction block.
The Diagnosis: Lyme Carditis
The patient was tested for Lyme disease and treated empirically with intravenous ceftriaxone.
Within 48 hours, his symptoms began to improve.
Lyme serology later returned positive, confirming the diagnosis.
After one month of antibiotic therapy, his heart rhythm had fully normalized.
[bctt tweet=”Lyme carditis can present as atrial fibrillation before progressing to heart block.” username=”DrDanielCameron”]
Why This Case Matters
This case highlights an important diagnostic challenge: Lyme carditis does not always begin with classic findings.
When atrial fibrillation is the initial presentation, clinicians may not consider Lyme disease early enough.
Key issue: relying on typical presentations can delay diagnosis.
Clinical Takeaway
Lyme carditis atrial fibrillation should be considered in patients from endemic areas who present with unexplained arrhythmias.
Clinical suspicion should remain high—even in the absence of a known tick bite or rash.
Early empiric antibiotic treatment may prevent progression to life-threatening heart block.
Key question: Could an atypical arrhythmia be the first sign of Lyme carditis?
Authors’ Key Points
- Lyme disease can present initially as atrial fibrillation
- Include Lyme carditis in the differential for supraventricular arrhythmias in endemic areas
- Start empiric antibiotics when suspicion is high—do not wait for test confirmation
Related Articles:
5 things to know about Lyme carditis
When Lyme disease mimics a heart attack
Cardiac problems in Lyme disease
References:
- Kostić T, et al. Manifestations of Lyme carditis. Int J Cardiol. 2017.
- Shabbir MA, et al. Lyme carditis presenting as atrial fibrillation. BMJ Case Rep. 2019.
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
Drs here don’t seem to think Lyme can cause Afib and won’t treat the Afib. I got Afib the same time I got Lyme, I was treated for Lyme but Afib persists, you have any ideas?
All I have been able to to do for my patients is to be sure their Lyme disease is successfully treated.
So, in your opinion no link between Lyme and Afib ?
I published the blog to encourage others work whether to add a tick borne illness to the long list of causes of atrial fibrillation. We do know that tick borne diseases can lead early to a electrical disturbance called heart block.
Lyme patient first 1998 with classic bulls eye rash over R thigh and No subsequent A-fib. Chronic Fatigue developed quickly afterwards. No antibiotic treatment ONLY large doses of natural supplements from Standard Process.
Exposure limited my competitive endurance athletic endeavors limiting my ability to train and perform. All hopes for return to high level competition slowly faded away.
Lyme exposure again 12 years later in June 2010 with classic Bulls eye rash over belly button and immediate horrible weakness and fatigue lasting 4-6 weeks. No serious Antibiotic treatment except 1 week Doxycycline orally but no significant progress. Large dosage of supplements again Now from PRL – Premier Research Labs with slow steady improvement over 6 weeks. Afib development about 4-5 months later for a few episodes during strenuous exercise training lasting about 4-5 hours each episode. Paroxysmal Afib to follow with episodes about 75% of the time with strenuous exercise. No traditional treatment.
1 year later went to strict Vegan diet with no Oils and no animal products and No nuts and seeds following Dr Caldwell Essylstein recommendations as per his best selling book Reversing Heart Disease.
4 weeks later Afib episodes stop for 3 months and I make mistake of returning to animal food consumption and quick return of paroxysmal Afib and now persistent Afib for past 5 years.
Vegan diet tried past 3 years off and with less and less changes in Afib episodes but good changes in cholesterol from Keto carnivore diet from 300 to 175. Elevated liver enzymes and renal enzymes with Keto carnivore diet. Return to normal levels with Vegan diet but now no improvement with consistent persistent Afib.
Desire to now focus upon treating my Afib in my blood and heart tissue to see if persistent Afib will change. Any natural remedy suggestions greatly appreciated.
There are so many factors related to atrial fibrillation. I was surprised that you did not try antibiotics for more than a week.