Syncope: One of the Differential Diagnoses Not to be Missed

Abstract

Introduction: Syncope is one of the most common causes for emergency visits and inpatient admissions. Etiologies range from benign causes like vasovagal to life-threatening arrhythmias. Careful history and examination is the key for appropriate diagnosis and management. We present a case of syncope in a young individual caused by bradycardia secondary to Lyme carditis.A 20-year-old male with no past medical history presented to the emergency department with an episode of syncope. Physical examination revealed bradycardia with heart rate (HR) of 50 beats/min. Further, electrocardiogram (EKG) showed first-degree atrio-ventricular (AV) block with PR interval more than 300 milliseconds. The patient was observed on telemetry. However, after few hours, repeat EKG showed complete AV block with HR at 30 beats/min. Cardiology was consulted and the patient had temporary pacemaker placed. Probing into the history further revealed that he was evaluated by his primary care physician around 2 weeks ago for macular non-itchy discrete erythematous rash on his extremity without any systemic symptoms, and was treated for contact dermatitis. Further, he revealed that he had been travelling around woods recently before the rash. Given suspicion of Lyme’s disease due to his history, he was started on intravenous ceftriaxone empirically and Lyme serology was sent. Patient’s bradycardia resolved in the next 48 hours. Temporary pacemaker was removed. Lyme serologies came back positive. He was discharged home on intravenous (IV) antibiotics. Discussion: Lyme carditis has been reported in approximately 4-10% of untreated adults in United States. AV conduction block of varying severity is the most common manifestation. Myopericarditis is less common and is usually mild. The diagnosis of Lyme carditis is established based on prevalence of the disease, clinical feature, and positive Lyme serology. High-grade AV block or first-degree heart block with PR interval more than 300 milliseconds should be hospitalized, monitored on telemetry, and treated with IV antibiotics until its resolution. AV conduction disturbance is usually short lived and can be managed with a temporary pacemaker. A permanent pacemaker should be avoided. Complete AV block typically resolves within 1 week, and minor conduction disturbances within 6 weeks. The prognosis of Lyme carditis is usually good.