Reversible heart block in lyme carditis

American Family Physician,  Oct, 1989  

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Reversible Heart Block in Lyme Carditis

Lyme disease is a tick-borne infection caused by the spirochete Borrelia burgdorferi. It is characterized by a pathognomonic erythema chronicum migrans rash, with associated fever, myalgias, arthralgias, headache, fatigue and lymphadenopathy. Lyme disease has been reported in over 30 states and is endemic in many parts of the northeastern United States. If Lyme disease is not treated with antibiotics, more than half of the patients will develop complications. The most common complication is arthritis, which affects 40 to 51 percent of patients. Neurologic complications occur in 7 to 19 percent of patients. The least well-documented complication, occurring in 4 to 10 percent of patients, is carditis. Antibiotic therapy with penicillin or tetracycline in the early stages of the disease may prevent or ameliorate later complications, but its role in the prevention or treatment of Lyme carditis has not been adequately assessed.

Lyme carditis usually begins three to six weeks after the initial illness and manifests as transient myocarditis with varying degrees of atrioventricular block. Nonspecific electrocardiographic changes, arrhythmias and evidence of left ventricular dysfunction occur in some patients. Temporary cardiac pacing is indicated in cases of high-grade atrioventricular block with hemodynamic instability. Complete heart block rarely persists for more than one week, and the long-term prognosis appears to be excellent. The need for permanent pacing is much less common. The diagnosis is made primarily on the basis of clinical impression and is confirmed by serologic testing.

McAlister and associates report four serologically confirmed cases of Lyme carditis in previously healthy young men (mean age: 45 years) who lived in endemic areas. Each patient presented with severe symptomatic atrioventricular block, and three had episodes of prolonged ventricular asystole. In two of the patients, permanent cardiac pacemakers were required (one was later removed). All four patients were treated with either tetracycline, a cephalosporin (cephradine or ceftriaxone) or parenteral penicillin. In each case, normal sinus rhythm returned, although one patient had second-degree block (Wenckebach) with atrial pacing at 120 beats per minute 16 months later.

Carditis may present before or many months after the initial antibody response. A high initial IgM response and subsequent IgG response in serial sera strongly suggest recent infection, which is usually the case in Lyme carditis. Direct culture of the spirochete allows a definitive diagnosis. Persistence of the spirochete within the myocardium is likely to be an intrinsic part of the pathophysiology of Lyme carditis. It remains unclear whether continued disease activity requires the persistence of a live spirochete or whether it results primarily from immune-mediated mechanisms. Consideration and prompt recognition of this potentially lethal, but reversible, cause of heart block are crucial to avoid inappropriate permanent pacemaker implantation.

COPYRIGHT 1989 American Academy of Family Physicians
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