Cardiac manifestations of Lyme disease.

Lyme disease is a vector-borne illness that can affect numerous organ systems during the early disseminated phase, including the heart. The clinical course of Lyme carditis is usually benign with most patients recovering completely. In rare instances, death from Lyme carditis has been reported. The cardinal manifestation of Lyme carditis is conduction system disease, which generally is self-limited. Heart block occurs usually at the level of the atrioventricular node but often is unresponsive to atropine sulfate. Temporary pacing may be necessary in more than 30% of patients, but permanent heart block rarely develops. Myocardial and pericardial involvement can occur but generally is mild and self-limited. Diagnosis is made by associating the clinical and historical features of borreliosis, such as previous tick bite, EM, or neurologic involvement, with electrocardiographic abnormalities and symptoms such as chest pain, palpitations, syncope, and dyspnea. Serologic studies and endomyocardial biopsy can support the diagnosis in the correct clinical setting, and MR imaging, echocardiography, and gallium scanning have utility in selected circumstances. No treatment has been shown clearly to attenuate or prevent the development of Lyme carditis, but mild carditis generally is treated with oral antibiotics and severe carditis with intravenous antibiotics in an effort to eradicate the infection and prevent late complications of Lyme disease. There is conflicting evidence regarding the role that B. burgdorferi plays in the development and progression of chronic congestive heart failure. Because of the significant false-positive ELISA rate in this population and the unclear benefit of antibiotic therapy, confirmatory Western blot analysis is recommended. Routine therapy and screening of patients with idiopathic dilated cardiomyopathy is of limited utility and should be reserved for patients with clear history of antecedent Lyme disease or tick bite.