Lyme disease is caused by infection with  Borrelia burgdorferi  in the United States in the Northeast and Upper Midwest regions.  It is a tick-borne illness that is associated significant controversy, though there is general consensus in the larger scientific community and the IDSA has guidelines (see below).  In general, it can have morbidity in that many symptoms linger during convalescent phase (myalgias, fatigue), even as the classic symptoms of acute infection (high fevers, rigors, erythema migrans rash) resolve relatively quickly with appropriate antibiotic therapy. Multiple clinical trials (most recently one published in NEJM this year) have shown no additional benefit of long term antibiotics for these symptoms once the initial therapy has been completed.

However, there is one key manifestation of Lyme that can be associated with mortality- carditis.  Carditis is a relatively rare event that  occurs in about 1% of all cases reported to the CDC.  Death from carditis is exceeding rare but is probably the most dangerous manifestation.  Since we are reaching the tail end of Lyme season (peak June-August for carditis), there are a few key features of Lyme carditis worth highlighting.

Cardiac involvement with Lyme is an early manifestation (Usually 2-5 weeks after tick bite).  It can occur with or just after erythema migrans rash, and similarly in relation to fever. It nearly always occurs in patient who have been untreated with antibiotics.  There is a suggestion that more recent data shows a decreased incidence due to more frequent recognition of acute Lyme which may prevent development of cardiac symptoms.

The conduction system is the usual site of cardiac manifestations.  Almost always this involves AV block. Much more rare is myocarditis and/pericarditis, with a suggestion of rare sequlae of cardiomyopathy. AV block can be 1st degree (usually asymptomatic) along with 2nd (type I and type II) and complete heart block. Patients often presents with dizziness or symptoms of lightheartedness due to bradycardia.  Patients may require temporary pacing but often recover with antibiotics.  The improvement is relatively rapid (often resolution or improvement in less than 1 week).

Most patients are given parental therapy while inpatient, but should be transitioned to oral therapy on discharge if they are stable (guideline recommendation). There is no data for superiority of IV therapy and this would not be a situation where outpatient IV therapy is usually indicated.

In 2013, the MMWR reported 3 cases of sudden cardiac death attributed to Lyme disease.  In two of the cases, the autopsy suggested acute myocarditis as the cause, but in a third case the patient had pancarditis  and a history of Wolfe-Parkinson-White syndrome. One wonders if he developed AV block and thus had a re-entrant circuit via the accessory pathway as the mechanism for sudden cardiac death.

Overall these cases represent a very tiny fraction of the burden of Lyme disease. Overall the prognosis with Lyme carditis is excellent and most patients are able to avoid permanent cardiac devices.  Patients with cardiac manifestations are usually symptomatic and it is reasonable to pursue EKG is patients with the appropriate symptoms, in the right season and geographical area. Admission for monitoring and prompt initiation of appropriate therapy also appears to helpful in these patients.

AV block due to Lyme is one of the interesting presentations of Lyme disease and one of the most satisfying to treat, as the improvement with antibiotics on the telemetry and EKG is often dramatic.

References:

IDSA Guideline for Lyme (Wormser et al)

Three Sudden Cardiac Deaths Associated with Lyme Carditis — United States, November 2012–July 2013 MMWR December 13, 2013 / 62(49);993-996

Notes from the Field: Update on Lyme Carditis, Groups at High Risk, and Frequency of Associated Sudden Cardiac Death — United States MMWR October 31, 2014 / 63(43);982-983

Robinson ML, Kobayashi T, Higgins Y, et al Lyme carditis. Infect Dis Clin North Am. 2015 Jun;29(2):255-68.

Berende A et al    Randomized Trial of Longer-Term Therapy for Symptoms Attributed to Lyme Disease.  N Engl J Med. 2016 Mar 31;374(13):1209-20.

[JAV]