Can Lyme Disease Be Fatal? When Untreated Lyme Carditis Leads to Death

Quick Answer: Lyme disease is rarely fatal, but untreated Lyme carditis can lead to dangerous heart rhythm abnormalities and sudden death. When cardiac symptoms appear, antibiotics should not be delayed.

Can you die from Lyme disease? While uncommon, untreated Lyme carditis can cause fatal cardiac arrhythmias. Two New England cases illustrate how diagnostic delays and waiting for laboratory confirmation before starting antibiotics contributed to preventable deaths.

Although rare, Lyme disease can occasionally be fatal when the infection affects the heart. This complication, known as Lyme carditis, can disrupt the heart’s electrical system and lead to dangerous arrhythmias.

The Reality of Lyme Disease Mortality

Lyme disease can lead to acute and chronic illness. But deaths from Lyme disease can occur. “Death can occur when Lyme carditis is untreated,” wrote Marx, from the Centers for Disease Control and Prevention (CDC), in the Annals of Internal Medicine. Before this report, only nine fatal cases were reported in the literature.

The CDC documented two additional fatal cases — both involving young to middle-aged adults with no prior cardiac history. Both patients had evidence suggesting Lyme disease. Both had diagnostic testing ordered. Yet neither received timely antibiotic treatment.

Why Lyme Carditis Can Become Life-Threatening

Lyme carditis occurs when the Lyme disease bacterium Borrelia burgdorferi affects the heart’s electrical conduction system. The infection can disrupt the signals that coordinate heartbeats, leading to conduction abnormalities such as heart block or dangerous arrhythmias.

In many patients, these cardiac complications respond quickly to antibiotic therapy. However, when treatment is delayed, electrical instability of the heart can occasionally lead to life-threatening arrhythmias.

Case 1: Waiting for an Infectious Disease Appointment

A 57-year-old man from Vermont presented to a primary care physician after one week of fever, fatigue, shortness of breath, and chest pain.

The evidence for Lyme disease included a disseminated erythema migrans rash, heart block, and a positive Lyme ELISA and IgM Western blot test. Yet the patient was not treated.

Eight days later, he presented to an emergency room with worsening symptoms. Physicians suspected Lyme disease, but antibiotics were not prescribed. Instead, a consultation with an infectious disease doctor was scheduled.

Only 12 days after his initial presentation — and before his scheduled appointment — the patient was found unresponsive.

This case illustrates the risks of delaying treatment while waiting for specialist evaluation. The patient had classic findings: EM rash, cardiac symptoms, and positive serology. Yet treatment was deferred.

Case 2: Before the First Dose of Antibiotics

A 49-year-old woman from Massachusetts presented to an emergency department with severe headache, nausea, and vomiting. She was diagnosed and treated for a headache.

Two weeks later, she saw her primary care physician and reported two episodes of syncope with bowel and bladder incontinence, persistent fatigue and nausea, and shortness of breath. An ECG during the office visit showed atrioventricular dissociation. Lyme disease tests were ordered.

Two days later, Lyme disease test results revealed a positive ELISA and IgM Western blot. She was prescribed doxycycline. But the next day — before she took the first dose — her cardiac monitoring recorded atrioventricular dissociation evolving to ventricular tachycardia.

She died before taking a single antibiotic pill.

Pathology Confirmed Lyme Carditis

In both patients, postmortem evaluation of heart tissue found lymphohistiocytic pancarditis with immunohistochemical and molecular evidence of Borrelia burgdorferi. Spirochetes were directly visualized in endocardial tissue from the Massachusetts patient.

The pathology confirmed what clinical suspicion had already suggested: active Lyme carditis requiring immediate treatment.

Why These Deaths Were Preventable

Lyme carditis was high on the list of possible diagnoses in both cases. Yet neither patient was treated empirically with antibiotics when Lyme disease testing was performed.

Guidelines recommend simultaneous initiation of empirical antibiotic therapy and Lyme serologic testing when Lyme carditis is suspected. Lyme carditis can progress rapidly. Waiting for confirmatory testing before starting antibiotics may lead to serious outcomes.

The Pattern of Diagnostic Delay

Both cases shared several concerning features:

• Multiple healthcare encounters before diagnosis
• Clear clinical evidence suggesting Lyme disease
• Testing ordered but treatment delayed while awaiting confirmation
• Death occurring during the wait for results or specialist evaluation

This pattern highlights broader challenges in recognizing Lyme disease when symptoms fall outside typical expectations.

Clinical Perspective

In my practice, I emphasize that Lyme carditis should be treated as a medical emergency. When a patient presents with new conduction abnormalities in a Lyme-endemic area — particularly a younger patient — empiric antibiotics should begin immediately while diagnostic testing is performed.

Most patients recover completely when treatment is started early. These cases serve as an important reminder that delays in recognition and treatment can occasionally lead to fatal outcomes.

Although deaths from Lyme carditis are uncommon, these cases highlight the importance of recognizing cardiac symptoms early and starting treatment promptly.

Frequently Asked Questions

Can you die from Lyme disease?

Yes. Although rare, untreated Lyme carditis can cause fatal cardiac arrhythmias. Prompt antibiotic treatment greatly reduces this risk.

How does Lyme disease affect the heart?

Borrelia burgdorferi can infiltrate heart tissue and disrupt the electrical conduction system, leading to heart block or other dangerous arrhythmias.

Should antibiotics be started before Lyme test results return?

When Lyme carditis is suspected, antibiotics are typically started at the same time testing is performed. Waiting for laboratory confirmation may delay life-saving treatment.

How quickly can Lyme carditis become serious?

Cardiac conduction abnormalities can progress rapidly — sometimes within hours or days — making early treatment critical.

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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