Lyme Carditis: Complete Heart Block in a Young Man

Lyme carditis can cause dizziness, fainting, palpitations, and chest pain
Atrioventricular block may progress rapidly to complete heart block
Prompt recognition may help avoid unnecessary permanent pacemaker placement

Can Lyme disease cause complete heart block? Yes. Lyme carditis can disrupt the heart’s electrical conduction system, producing atrioventricular block that may progress rapidly to complete heart block. In this case, a 37-year-old man presented with dizziness and recurrent fainting after several tick bites.

Lyme carditis often presents with nonspecific symptoms, including lightheadedness, fainting, shortness of breath, palpitations, and chest pain. These and other signs of Lyme carditis may occur before the underlying conduction abnormality is recognized. However, some estimates have suggested that asymptomatic cardiac involvement may occur in up to 30% of cases.

The most common clinical manifestation “is AV block, which can be acute in onset and can rapidly progress to complete heart block,” wrote Carnazzo and colleagues.

Complete Heart Block Following Several Tick Bites

In their article, “Lyme disease presenting as complete heart block in a young man: Case report and review of pathogenesis,”¹ Carnazzo and colleagues described a young man who developed complete heart block as a complication of Lyme disease months after several tick bites.

Younger adults, particularly males, have been reported more often among patients with Lyme carditis. The authors emphasized that clinicians should consider Lyme carditis when a younger patient develops otherwise unexplained high-grade heart block, particularly in a Lyme-endemic area.

The patient was a 37-year-old man living in northwestern Wisconsin. He presented to the emergency department after experiencing two episodes of syncope without warning over a five-day period.

During that time, he also developed increasingly frequent episodes of dizziness and near-syncope.

He reported fever, chills, muscle aches, and a red rash on both lower legs that had appeared three weeks earlier. The rash had resolved by the time he sought emergency care.

Approximately two months before his symptoms began, the patient had removed several ticks from his left thigh and groin.

Why Lyme Carditis Can Be Missed

Lyme carditis can be difficult to recognize when a patient does not have an obvious erythema migrans rash at presentation or cannot recall a tick bite. A rash may have resolved before cardiac symptoms develop, as occurred in this case.

Symptoms such as dizziness, fainting, shortness of breath, palpitations, and chest pain may initially appear nonspecific. However, these symptoms can signal a potentially serious cardiac conduction abnormality, particularly when accompanied by an unusually slow or changing heart rate.

Patients with chest pain, fainting, severe dizziness, significant shortness of breath, or a suspected heart rhythm disturbance should seek immediate medical evaluation.

ECG Reveals Complete Heart Block

An electrocardiogram revealed complete heart block. Because of the severity of the conduction abnormality, the patient required insertion of a temporary pacemaker.

Lyme serology, including Western blot testing, was positive. The patient was diagnosed with Lyme carditis and treated with intravenous ceftriaxone.

After nine days, the heart block had completely resolved.

This recovery illustrates why recognizing Lyme carditis is important before placing a permanent pacemaker. Temporary pacing may be lifesaving while antibiotic treatment is initiated, but a permanent pacemaker may not be necessary when the heart block is reversible.

Signs That Should Raise Suspicion for Lyme Carditis

Possible features of Lyme carditis include:

• Lightheadedness or dizziness
• Syncope or near-syncope
• Heart palpitations
• Chest pain
• Shortness of breath
• An unusually slow or changing heart rate
• New atrioventricular block or another conduction abnormality
• Recent tick exposure or outdoor activity in a Lyme-endemic area
• A current or previous erythematous rash
• Fever, fatigue, chills, muscle aches, or joint pain

When a patient presents with unexplained high-grade AV block, the history should include questions about possible tick exposure, outdoor activities, travel to a Lyme-endemic area, a current or previous rash, and constitutional symptoms associated with Lyme disease.

Frequently Asked Questions

Can Lyme disease cause complete heart block?

Yes. Lyme carditis can interfere with the heart’s electrical conduction system and cause varying degrees of atrioventricular block, including complete or third-degree heart block.

Can Lyme carditis come and go?

Yes. The severity of atrioventricular block associated with Lyme carditis can fluctuate and may progress rapidly. A patient’s cardiac conduction can change over minutes, hours, or days, making close monitoring important when high-grade heart block is suspected.

Does Lyme carditis show up on an ECG?

An ECG may reveal first-degree, second-degree, or complete atrioventricular block. Because the degree of heart block can change rapidly, patients with suspected Lyme carditis may require repeated ECGs or continuous cardiac monitoring.

Can Lyme carditis occur without a rash?

Yes. A patient may not recall an erythema migrans rash, or the rash may have resolved before cardiac symptoms appear. The absence of a visible rash at presentation does not exclude Lyme carditis.

Can Lyme carditis require a pacemaker?

Severe heart block may require temporary pacing while antibiotic treatment is initiated. Permanent pacemakers are less commonly needed because conduction abnormalities associated with Lyme carditis may resolve with appropriate treatment.

Clinical Takeaway

Lyme carditis should be considered in younger patients with otherwise unexplained high-grade AV block, particularly when there is possible tick exposure, outdoor activity in an endemic area, a recent rash, or constitutional symptoms. Timely recognition allows cardiac monitoring, temporary pacing when necessary, and prompt antibiotic treatment.

Fainting, dizziness, palpitations, or chest pain accompanied by unexplained heart block may be an early sign of Lyme carditis—even when a tick bite or rash is not evident at presentation.

Related Articles

Successful Removal of Pacemakers for Lyme Carditis
Lyme Carditis Causes Complete Heart Block in a 26-Year-Old Man
Lyme Disease Symptoms Guide

References

1. Carnazzo MC, Scholin C, Shweta F, Calvin AD. Lyme disease presenting as complete heart block in a young man: Case report and review of pathogenesis. IDCases. 2023;32:e01799. doi: 10.1016/j.idcr.2023.e01799. PMID: 37234726; PMCID: PMC10205533.

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