Most people associate Lyme disease with a bullseye rash and joint pain — not their heart. But in a small number of cases, the bacteria that cause Lyme disease can reach the heart tissue and interfere with its electrical system. This complication, called Lyme carditis, is uncommon, serious, and — with prompt treatment — very treatable.
Medically reviewed by Elyssa A. Blissenbach, MD, board-certified internal medicine physician.
What Is Lyme Carditis?
Lyme carditis occurs when Borrelia burgdorferi bacteria enter the heart tissue and disrupt the signals that coordinate the heartbeat. The most characteristic problem is atrioventricular (AV) block — a slowing or interruption of the electrical signal between the upper and lower chambers of the heart. According to the CDC, carditis occurs in roughly one out of every hundred reported Lyme disease cases, typically within weeks to months of the initial infection.
Symptoms That Should Not Wait
Lyme carditis can progress quickly — mild symptoms can become a high-degree heart block within days. Seek prompt medical attention if you have possible Lyme exposure and notice:
- Lightheadedness or fainting spells
- Heart palpitations or a noticeably slow heartbeat
- Chest pain or pressure
- Shortness of breath, especially with mild activity
Because many patients never saw a tick or a rash, it is important to mention any outdoor exposure, hiking, or travel to your physician — especially if these symptoms appeared after a summer flu-like illness.
How It Is Diagnosed and Treated
Evaluation typically includes an electrocardiogram (ECG) alongside two-step Lyme antibody testing. The encouraging news: Lyme carditis usually responds well to antibiotics. Patients with significant heart block may be monitored in hospital and occasionally need temporary pacing while the antibiotics take effect, but conduction usually recovers — often within a week or two of starting treatment. Permanent pacemakers are rarely needed when the condition is recognized promptly.
An internal medicine physician experienced in Lyme disease care can coordinate the cardiac workup and antibiotic treatment together, and rule out other causes of conduction problems.
Frequently Asked Questions
How soon after a tick bite can Lyme carditis develop?
Typically within one to two months of infection, though the window varies. It can be the first noticeable sign of Lyme disease — some patients never recall a rash.
Is Lyme carditis fatal?
Deaths are very rare. The danger is an unrecognized high-degree heart block, which is why new fainting or palpitations after possible tick exposure deserve urgent evaluation.
Does the heart damage last?
In most treated patients, no — the electrical disturbance usually resolves with antibiotics, and long-term heart problems are uncommon.
Northeast Florida Internal Medicine treats Lyme disease and other tick-borne illnesses in person in Jacksonville and via telemedicine for patients in Florida, Georgia, Alabama, South Carolina, North Carolina, and Virginia. Contact us to schedule a consultation.
This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified physician with any questions about a medical condition.