The Great Imitator: A Case of Lyme Carditis Mimicking ST Elevation Myocardial Infarction.

Lyme disease, caused by Borrelia burgdorferi and transmitted via Ixodes ticks, is a common vector-borne illness in the United States, with an estimated 476,000 annual cases. While primarily known for its neurological and rheumatological manifestations, Lyme disease can also involve the cardiac system, known as Lyme carditis, which occurs in about 4% to 10% of cases. This case report details a rare instance of Lyme carditis presenting as ST-segment elevation myocardial infarction (STEMI) in a 31-year-old female with no significant medical history. The patient exhibited symptoms of chest pressure and shortness of breath, with laboratory results showing significantly elevated troponin levels and other indicative markers. Notably, cardiac catheterization revealed no coronary occlusion, suggesting an alternative diagnosis to acute coronary syndrome (ACS). Further testing confirmed Lyme carditis through positive serological tests for Lyme-specific IgM antibodies. The case underscores the importance of considering Lyme myopericarditis in differential diagnoses for STEMI in Lyme-endemic areas and in patients without typical risk factors for coronary artery disease. This report aims to increase clinical awareness of this condition, highlighting the need for thorough investigation in atypical cardiac presentations.