Tuesday, February 25, 2014

Sudden death due to Lyme carditis

A recent report from MMWR:

Symptomatic infection of the heart is rare in recognized Lyme disease cases and usually resolves promptly with appropriate antibiotic therapy. Nonetheless, cardiac involvement occasionally can cause life-threatening cardiac conduction abnormalities. During November 2012–July 2013, one woman and two men (ranging in age from 26 to 38 years) from high-incidence Lyme disease states experienced sudden cardiac death and, on postmortem examination, were found to have evidence of Lyme carditis.

This represents a higher frequency than what has been reported before. These individuals had no prior history or extracardiac manifestations of Lyme disease.

From an associated Medscape article:

"The Borrelia burgdorferi spirochetes actually make it into the heart tissue. Whether the resulting carditis is due to the spirochetes themselves or to the immune responses to them or to a combination of both is unclear," Dr. Forrester said.
The most common manifestation of Lyme carditis is atrioventricular (AV) conduction blockade. Dr. Forrester said that sudden cardiac death might be the result of the conduction abnormality leading to fatal arrhythmia...
"The current article further reiterates the importance of identification of Lyme carditis as a cause of heart block. I think this is more relevant to primary care physicians who manage the patients at the front end. The diagnosis of Lyme carditis can be challenging if it is the initial presentation of the disease process and [the] patient does not remember having a tick bite. AV block may be the first and only sign of Lyme disease," said Paras Karmacharya, MD...
"Although more than 90% of patients with Lyme carditis have complete recovery, patients with more severe conduction system disturbances (first-degree AV block with a PR interval greater than 0.3 seconds, second- or third-degree AV block) should be referred immediately to the emergency department and hospitalized in a coronary care unit for treatment with intravenous antibiotics like ceftriaxone or high-dose penicillin G. Insertion of a temporary transvenous pacemaker may be required. As in the case described in our article, the degree of heart block can fluctuate from first degree to second degree to complete AV block very quickly in minutes to hours, so careful observation is prudent. Treatment with an antibiotic can revert the AV block within 48 hours of therapy, so identification of this potentially reversible cause of heart blocks may help prevent significant morbidity and mortality," Dr. Karmacharya said.
"Once you start treatment for Lyme carditis, the prognosis is excellent," Dr. Forrester emphasized.

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