Lyme Carditis Symptoms May Go Undiagnosed in Mexico

Lyme carditis symptoms can be difficult to recognize, particularly in regions where Lyme disease is not widely acknowledged. Lyme carditis occurs when Borrelia burgdorferi infects the heart and disrupts the electrical conduction system. A case report from Mexico highlights how delayed recognition of Lyme carditis may lead to serious cardiac complications.

The authors highlight the case of a 23-year-old woman who presented to their hospital with dyspnea and chest pain. An electrocardiogram (ECG) revealed a third-degree atrioventricular (AV) block — a potentially life-threatening heart rhythm disturbance that can occur with Lyme carditis.

A temporary pacemaker was implanted. After an exhaustive work-up for other causes of heart block, the woman was eventually tested for Lyme disease. While Lyme carditis symptoms can present in a broad range of ways, test results were positive using the Centers for Disease Control and Prevention (CDC) two-tier Western blot criteria.

Despite treatment with a three-week course of intravenous ceftriaxone, the patient ultimately required placement of a permanent pacemaker. “At 3-month follow-up, she was still dependent on pacing,” writes Carrizales-Sepulveda and colleagues.

Delayed Recognition of Lyme Carditis Symptoms

The authors argue that the patient lived in an endemic region and had visited the hospital four weeks earlier with symptoms consistent with Lyme carditis.

According to the CDC, a region may be considered endemic for Lyme disease if at least two confirmed locally acquired cases have been reported or if established populations of infected tick vectors are present.

However, the medical community in Mexico has been reluctant to acknowledge Lyme disease as a possible cause of heart block. Officials have argued that “there is no convincing evidence that Borrelia burgdorferi is present in Mexico.”

READ MORE: Which treatment guidelines should you follow for Lyme carditis?

Evidence of Lyme Disease in Mexico

Despite such resistance, Carrizales-Sepulveda and colleagues report measurable Lyme disease exposure in Mexico.

The authors describe a seroprevalence of 6.2% in northeastern Mexico and 3.4% in Mexico City using a two-tier approach with enzyme-linked immunosorbent assay (ELISA) followed by Western blot.

Unfortunately, these results were dismissed as false positives, the authors write.

Furthermore, their Lyme carditis diagnosis was questioned, with critics suggesting that the patient’s advanced AV block may have had another cause that had not been fully investigated.

Considering Lyme Carditis in Patients With Heart Block

The authors recommend that Lyme carditis remain part of the differential diagnosis for patients presenting with unexplained heart block in Mexico.

“We agree that in our country other causes should be ruled out first; however, there is no reason to exclude Lyme carditis as a possible diagnosis,” they write.

They conclude that Lyme disease in Mexico may be under-recognized, underdiagnosed, and underreported. Clinicians should consider Lyme carditis when evaluating patients with unexplained AV block, even in regions where Lyme disease is thought to be uncommon.