PT - JOURNAL ARTICLE AU - Abir Zainal AU - Amir Hanafi AU - Ninad Nadkarni AU - Mahmood Mubasher AU - Deeraj Lingutla AU - Ryan Hoefen TI - Lyme carditis presenting as atrial fibrillation AID - 10.1136/bcr-2018-228975 DP - 2019 Apr 01 TA - BMJ Case Reports PG - e228975 VI - 12 IP - 4 4099 - http://casereports.bmj.com/content/12/4/e228975.short 4100 - http://casereports.bmj.com/content/12/4/e228975.full SO - BMJ Case Reports2019 Apr 01; 12 AB - The incidence of Lyme disease in the USA is 8 per 100 000 cases and 95% of those occur in the Northeastern region. Cardiac involvement occurs in only 1% of untreated patients. We describe the case of a 46-year-old man who presented with chest pressure, dyspnoea, palpitations and syncope. He presented initially with atrial fibrillation with rapid ventricular response, a rare manifestation of Lyme carditis. In another hospital presentation, he had varying degrees of atrioventricular block including Mobitz I second-degree heart block. After appropriate antibiotic treatment, he made a full recovery and his ECG normalised. The authors aim to urge physicians treating patients in endemic areas to consider Lyme carditis in the workup for patients with atrial fibrillation and unexplained heart block, as the associated atrioventricular nodal complications may be fatal.