What is Lyme Carditis?

Lyme disease, caused by the spirochete Borrelia burgdorferi, can lead to Lyme carditis, a rare but serious complication where the bacteria infiltrate heart tissue, often causing atrioventricular (AV) block. This invasion can disrupt the normal electrical activity that controls the heartbeat. Lyme carditis occurs in approximately 1-10% of untreated Lyme disease cases, typically during the early disseminated phase (weeks to months after infection). Symptoms include lightheadedness, fainting, shortness of breath, chest pain, and heart palpitations, often accompanied by other Lyme symptoms like erythema migrans (EM) rash or flu-like illness.

• Most commonly it causes atrioventricular (AV) block, ranging from mild (first-degree) to severe (third-degree), which can impair the heart's ability to pump blood effectively.
• Symptoms include palpitations, chest pain, shortness of breath, dizziness, fainting, or fatigue, though some patients may be asymptomatic.
• Other cardiac issues, like myocarditis or pericarditis, are less common but possible.

Diagnosing Lyme carditis involves considering a patient's symptoms, medical history (including possible tick bites or living in an area where Lyme disease is common), and physical examination. Tests that may be used include:

• Electrocardiogram (ECG): To assess the heart's electrical activity and identify any heart block or rhythm abnormalities.
• Blood tests to look for antibodies to Borrelia burgdorferi, the bacteria that cause Lyme disease.
• Holter monitor: A portable ECG that records the heart's rhythm over a longer period (usually 24-48 hours) to detect intermittent problems.
• Echocardiogram: An ultrasound of the heart to evaluate its structure and function.
• In some cases, more advanced tests like a cardiac MRI or even a myocardial biopsy might be necessary.

People with untreated Lyme disease, especially within weeks to a few months after infection, are at higher risk. It’s more common in young men for reasons not fully understood.

The primary treatment for Lyme carditis is antibiotics to eradicate the Borrelia burgdorferi bacteria. Commonly used antibiotics include doxycycline, amoxicillin, or ceftriaxone. The duration of treatment depends on the severity of the carditis. Hospitalization may be needed for severe cases, especially with high-degree AV block, to monitor and manage heart rhythm (e.g., temporary pacemaker in rare cases). Most patients recover fully with timely treatment, often within weeks. In cases of significant heart block or severe symptoms, a temporary pacemaker may be necessary to ensure a stable heart rhythm until the antibiotics have a chance to work and the inflammation subsides. Permanent pacemakers are rarely needed as the heart's electrical function usually recovers with antibiotic treatment.

Not usually — it's rare (only ~1% of Lyme cases). But if someone has Lyme disease symptoms *plus* any signs of heart trouble, it’s worth getting checked ASAP. If you suspect Lyme carditis or have symptoms, seek medical attention promptly, as early treatment is critical to prevent complications. The prognosis for Lyme carditis is generally very good with prompt diagnosis and appropriate antibiotic treatment. Most patients experience a full recovery of their heart function. The AV block typically resolves within days to weeks of starting antibiotics. It's important to see a doctor as soon as possible if you experience any of the symptoms of Lyme carditis, especially if you also have symptoms of Lyme disease or live in or have visited an area where Lyme disease is common. Early diagnosis and treatment can prevent more serious complications.

Co-infections, such as those caused by Anaplasma phagocytophilum (human granulocytic anaplasmosis), Babesia microti (babesiosis), or Bartonella species, are common in Lyme disease patients because the same ticks (Ixodes spp.) can transmit multiple pathogens. While Lyme carditis is primarily linked to Borrelia burgdorferi, co-infections may complicate the clinical picture, potentially exacerbating cardiac symptoms or mimicking carditis-like presentations. However, direct evidence linking co-infections to carditis is limited and less well-documented compared to Lyme carditis alone.

Anaplasmosis: Caused by Anaplasma phagocytophilum, this co-infection can lead to systemic inflammation and, in rare cases, cardiac complications. There are case reports of anaplasmosis associated with myocarditis or pericarditis, but these are not as common as Lyme carditis. Anaplasmosis typically presents with fever, leukopenia, and thrombocytopenia, which can overlap with Lyme symptoms, making diagnosis challenging.

Babesiosis: Caused by Babesia microti, this protozoan infection primarily affects red blood cells, leading to hemolytic anemia. While babesiosis is not directly associated with carditis, severe cases can cause cardiovascular stress due to anemia or systemic inflammation, potentially worsening cardiac symptoms in Lyme carditis patients.

Bartonella: Bartonella species, such as B. henselae, are less commonly transmitted by Ixodes ticks but can be co-infections in some cases. Bartonella is known to cause endocarditis in rare instances, particularly in immunocompromised patients. There is anecdotal evidence suggesting Bartonella may contribute to arrhythmias or other cardiac issues in Lyme patients, but this is not well-established in the literature.

Clinical Overlap and Diagnosis Challenges: Co-infections can obscure the diagnosis of Lyme carditis because symptoms like fever, fatigue, and myalgia overlap. Serologic testing for Lyme disease (ELISA followed by Western blot) is critical, but early-phase tests may be negative. Co-infection testing (e.g., PCR or serology for Anaplasma or Babesia) is recommended in endemic areas, especially if cardiac symptoms are present.

Lyme carditis is a serious cardiac complication of Lyme disease, primarily affecting young adults and often presenting as atrioventricular (AV) block. It occurs when Lyme bacteria invade the heart tissue, causing heart block, which can vary in severity and may fluctuate rapidly. Early diagnosis and treatment with antibiotics can prevent unnecessary pacemaker implantation and resolve the condition.