Abstract
Acute pericarditis with pericardial effusion caused by Lyme disease is very rare and requires excluding other more common possible causes of acute pericarditis. Common causes of acute pericarditis include viral and bacterial infections, connective tissue disorders such as rheumatoid arthritis, systemic lupus erythematosus, or scleroderma, or trauma to the heart, such as from a heart attack or heart surgery. While Lyme disease is mainly known for cardiac effects such as heart blocks and arrhythmias, it can also rarely cause pericarditis with pericardial effusion. In this case report, we present a patient with typical manifestations of acute pericarditis with pericardial effusion, and the patient was found to be positive for Lyme disease. Following pericardiocentesis and a three-week course of doxycycline, her symptoms resolved.