Lyme Carditis Presenting as Complete Heart Block in a Young Woman From Mexico

A previously healthy woman presented to the emergency department with sudden-onset
dyspnea and chest pain. Four days prior to admission, she experienced a syncopal episode.
Electrocardiogram (EKG) findings revealed a third-degree atrioventricular (AV) heart block.

The patient, a resident of Nuevo León, Mexico, reported travel within the previous four
weeks to a region considered endemic for Lyme disease.

According to Jiménez-Castillo and colleagues
, seroprevalence studies in northeastern Mexico
demonstrated rates of 3.91% in Nuevo León, 6% in Coahuila, and 14% in Tamaulipas, highlighting
regional exposure risk to Borrelia burgdorferi.

Lyme Disease Suspected Despite Absence of Tick Bite or Rash

The woman did not recall a tick bite and denied having an erythema migrans rash. However,
Lyme disease was suspected based on the absence of an alternative etiology for her cardiac
findings and her recent travel history to an endemic area.

[bctt tweet=”23-year-old woman from northeastern Mexico diagnosed with Lyme carditis after presenting with complete heart block.” username=”DrDanielCameron”]

Diagnosis and Treatment of Lyme Carditis

The patient was treated empirically with a 21-day course of intravenous ceftriaxone and
received a temporary pacemaker for symptomatic heart block.

Serologic testing confirmed the diagnosis. “An enzyme-linked immunosorbent assay for IgM
antibodies against Borrelia burgdorferi was reported positive,” the authors noted,
“and later corroborated by a positive immunoblot analysis.”

Despite antimicrobial therapy, the patient continued to require cardiac pacing, and a
permanent pacemaker was ultimately placed.

Clinical Implications

The authors emphasize the importance of considering Lyme carditis in young patients who
present with high-degree AV block without an apparent cause, particularly in those with
travel or residence in endemic regions.

Note:
Further research is needed to better understand the reasons for the high prevalence of
Borrelia burgdorferi infection in certain regions of Mexico.