A Case Report of Lyme Carditis Presenting as New-Onset Atrial Flutter in the Emergency Department.

Lyme disease (LD) is the most common vector-borne disease in the United States and has several well-known pathologic sequelae if not treated, including third-degree atrioventricular block. However, an association between Lyme carditis and atrial arrhythmias has been described in some cardiology literature but has not been reported in emergency medicine or wilderness medicine literature. This case report describes an older adult with new-onset atrial flutter with rapid ventricular rate in the setting of early disseminated LD, who ultimately was treated with antibiotics, had resolution of atrial flutter, and has had no recurrence. As cardiac inflammation secondary to organ infection may manifest as multiple forms of arrhythmia, this case report highlights the importance of considering LD as a differential diagnosis when treating tick-exposed patients with new cardiac arrhythmias, including atrial flutter.