256 Syncope in an Endurance Athlete with 9 Second Ventricular Pauses - not What You Expect - A Case Report

Abstract

Endurance sports have become increasingly popular over the last 25 years [[1]Scheer V. Participation Trends of Ultra Endurance Events.Sports Medicine and Arthroscopy Review. 2019; 27: 3-7Crossref PubMed Scopus (74) Google Scholar]. Bradycardia & atrioventricular (AV) block in endurance athletes are well described [[2]Viitasalo M. Kala R. Eisalo A. Ambulatory electrocardiographic recording in endurance athletes.Heart. 1982; 47: 213-220Crossref Scopus (150) Google Scholar]. We present a case of a 52 year old male endurance athlete with syncope on standing. He frequently completed marathons, triathlons, 200km cycles & meditation regularly. On cardiac monitoring he had sinus bradycardia with AV block (ventricular pauses) up to 7.8 seconds. He was awake & asymptomatic during these events. He had no features of obstructive sleep apnoea. Bloods were normal (full blood count, electrolytes & thyroid function). Therefore a loop recorder was inserted & he was discharged. Cardiac magnetic resonance imaging was normal & an exercise stress test showed normal chronotropic response (exceeded target heart rate). The loop recorder also showed asymptomatic ventricular pauses up to 9 seconds. All events had concurrent sinus bradycardia & AV block suggesting a physiological mechanism rather than brady-arrhythmia. Some of these events occurred during meditation. The patient reported a history of postural lightheadedness with presyncopal episodes corresponding with a heart rate of 50-75 beats per minute. Therefore his syncope was felt to be due to postural hypotension. This case supports the argument that sinus bradycardia & lengthy ventricular pauses (9 seconds) in an endurance athlete can be incidental, possibly due to high vagal tone. Meditation may contribute. Thorough investigation can avoid unnecessary pacemaker insertion.