A 33-year-old man with cystic fibrosis 220 days removed from bilateral lung transplantation presented with 1 week of intermittent fevers (maximum 102°F), malaise, bilateral lower extremity edema, unintentional weight gain (8 pounds), and 2 days of dyspnea on exertion. His posttransplant course was complicated by persistent leukopenia with intermittent neutropenia attributed to his antirejection regimen of mycophenolate mofetil and tacrolimus. On presentation his temperature was 98.9°F, his heart rate was 84 beats per minute, his blood pressure was 148/83 mm Hg, and he was breathing 20 times per minute with an oxygen saturation of 98% on room air. Bi-basilar crackles and trace pretibial edema were noted on clinical examination. Pronounced first-degree atrioventricular block (Figure, panel A) was detected on his electrocardiogram. Chest radiography exhibited bilateral patchy infiltrates with cephalization and Kerley B-lines consistent with mild pulmonary edema. Initial serology was remarkable for an N-terminal pro B-type natriuretic peptide level of 8050 pg/ml and an absolute neutrophil count of 0.5 10e9/L. Mycophenolate mofetil was discontinued, and the patient was treated with granulocyte colony-stimulating factor and broad spectrum antibiotics owing to suspicion of microbial infection. Subsequent echocardiography uncovered new moderate tricuspid and mitral regurgitation without visible valvular vegetation (Figure, panel B). There was no evidence of chamber enlargement, systolic dysfunction, or diastolic dysfunction. Intravenous furosemide was prescribed for diuresis. The patient developed facial droop (right > left) and dysarthria 72 hours after admission. T1-weighted, gadolinium-enhanced magnetic resonance imaging of his brain displayed abnormal enhancement of the distal cisternal, intracanalicular, and labyrinthine right facial nerve segments (Figure, panel C, arrow) as well as the mastoid left facial nerve segments, consistent with bilateral Bell’s palsy. Analysis of cerebrospinal fluid revealed predominantly lymphocytic pleocytosis and elevated protein. The presence of Borrelia burgdorferi immunoglobulin M, but not immunoglobulin G, was detected in the patient’s serum by Western blot, suggesting early, disseminated Lyme disease. The patient later recalled sustaining several tick bites on his farm. He was prescribed a 28-day course of intravenous ceftriaxone and was discharged after a 10-day hospitalization at his baseline weight, with resolution of neutropenia and heart block. At 6-month follow-up he was asymptomatic, his examination results were normal, and echocardiography revealed only trace mitral and tricuspid insufficiency. The B-type natriuretic peptide level was 170 pg/mL.
Lyme borreliosis is a common tick-borne spirochete infection. Typical symptoms include fever, myalgia, erythema migrans, arthritis, and facial palsy.1 Lyme carditis, representing only 1.1% of cases, occurs when the spirochete invades the heart wall, triggering a macrophage-mediated inflammatory response often concentrated in the connective tissue near the atrioventricular junction.1, 2 The predominant clinical manifestation is self-limited atrioventricular nodal block, although fulminant cases of myopericarditis and cardiomyopathy have been reported.1 Heart valve involvement is extremely rare, with only 2 reported biopsy-proven cases of Lyme endocarditis.3, 4 We found 2 reports of possible Lyme endocarditis manifesting with an aortic valve vegetation5and rupture of the mitral valve chordae6 in the setting of positive Lyme titers. We also found 2 reports of Lyme carditis presenting with transient mitral regurgitation due to poor leaflet coaptation, possibly resulting from inflammation and edema extending into the valve tissue.2, 7 This is a plausible mechanism for the transient mitral and tricuspid valve insufficiency observed in our case, particularly because there was no evidence of leaflet prolapse, restriction, or destruction from visible infectious vegetation. Dissemination of the spirochete was likely mediated by immunosuppression, which may also explain the extent of cardiac involvement. Prompt antibiotic therapy may have prevented permanent and severe valve malfunction.
The cardiac sequelae of Lyme borreliosis are generally reversible if recognized early. Thus, Lyme borreliosis should be considered when evaluating unexplained valve dysfunction, heart block, cardiomyopathy, or myopericarditis in endemic areas.
To read this article in its entirety please visit our website.
– Ankit Maheshwari, MD, Robert J. Bache, MD
This article originally appeared in the October 2017 issue of The American Journal of Medicine.
