Can Lyme Disease Cause Endocarditis?

Lyme disease may rarely involve heart valves.
Culture-negative endocarditis can delay diagnosis.
PCR testing of valve tissue may help confirm infection.

A 40-year-old man presented to the emergency department with a severe headache lasting 5 days along with intermittent numbness in his left arm.

CT scan and MRI of the brain revealed an acute subarachnoid hemorrhage, and the patient was admitted for management of acute stroke.

Neurologic complications can occasionally occur in infective endocarditis because of embolic or vascular events.

Mitral Valve Abnormalities Raise Concern

Additional cardiac testing demonstrated a density on the mitral valve along with perforation of the valve leaflet and severe mitral regurgitation.

“We present a new case of culture-negative Lyme endocarditis highlighting clinical characteristics that should trigger tissue PCR to diagnose this pathogen in cases of culture-negative endocarditis,” the authors wrote.

Because of progressive valve damage and severe regurgitation, the patient ultimately underwent:

Aortic valve replacement
Mitral valve repair
Median sternotomy with cardioplegic arrest

Culture-Negative Endocarditis and Lyme Disease

Because the patient had exposure to cats, farm animals, and a history of squirrel hunting, clinicians also evaluated him for other infectious causes including Coxiella and Bartonella.

One week after discharge, PCR testing of mitral valve tissue returned positive for Borrelia burgdorferi.

The patient was subsequently treated successfully with doxycycline.

Why the Diagnosis Was Missed

There was initially a low suspicion for Lyme disease endocarditis because the patient did not recall a tick bite or prior erythema migrans rash.

The authors also noted that follow-up Lyme serology was never repeated after the patient’s initial presentation.

“Convalescent serology was never rechecked 3 weeks after this initial presentation, and consequently he went undiagnosed, allowing for late complications to arise that may have been avoided with follow-up titers.”

What Is Culture-Negative Endocarditis?

Culture-negative endocarditis occurs when blood cultures fail to identify the infectious organism despite evidence of heart valve infection.

Potential causes may include:

Fastidious bacteria
Prior antibiotic exposure
Unusual infectious organisms
Intracellular pathogens

Rarely, Borrelia burgdorferi may be identified through PCR testing of infected valve tissue.

Lyme Carditis and Cardiac Complications

Lyme carditis most commonly affects the electrical conduction system of the heart, potentially leading to heart block and rhythm abnormalities.

However, rare cardiac manifestations involving heart valves, myocarditis, or endocarditis have also been described.

Because these presentations are uncommon, diagnosis may be delayed.

Clinical Perspective

The authors emphasized that Borrelia species should remain in the differential diagnosis of culture-negative endocarditis, particularly when valve pathology appears unusual.

Cases like this highlight the potential value of PCR testing when routine cultures remain negative despite ongoing clinical suspicion.

FAQ: Lyme Disease Endocarditis