Does deep bradycardia increase the risk of arrhythmias and syncope in endurance athletes?

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Bibliographic Details
Title translated into German:Erhöht eine tiefe Bradykardie bei Ausdauersportlern das Risiko für Herzrhythmusstörungen und Synkope?
Author:Matelot, David; Schnell, F.; Khodor, N.; Endjah, N.; Kervio, G.; Carrault, G.; Thillaye du Boullay, N.; Carré, F.
Published in:International journal of sports medicine
Published:37 (2016), 10, S. 792-798, Lit.
Format: Publications (Database SPOLIT)
Publication Type: Journal article
Media type: Electronic resource (online) Print resource
ISSN:0172-4622, 1439-3964
Online Access:
Identification number:PU201610007306

Author's abstract

The aim of this study was to evaluate whether endurance athletes who exhibit deep bradycardia are more prone to arrhythmias and reflex syncope than their non-bradycardic peers. 46 healthy men (ages 19–35) were divided into 3 groups based on whether they were sedentary (SED,<2 h/week) or endurance trained (ET,>6 h/week), and non-bradycardic (NB, resting heart rate (HR)≥60 bpm) or bradycardic (B, resting HR<50 bpm). Resting HR was lower in ETB vs. ETNB and SED (43.8±3.1, 61.3±3.3, 66.1±5.9 bpm, respectively; p<0.001). Thus, 16 SED, 13 ETNB and 17 ETB underwent resting echocardiography, maximal exercise test, tilt test (TT) and 24 h-Holter ECG. Subjects were followed-up during 4.7±1.1 years for training, syncope and cardiac events. Our results showed that incidence of arrhythmias and hypotensive susceptibility did not differ between groups. During follow-up, no episode of syncope or near-syncope was reported. However, cardio-inhibitory syncope occurrence tended to be higher in ETB. Left ventricular end-diastolic diameter index was increased in ETB vs. ETNB and was correlated with resting HR (r=− 0.64; p<0.001). As a result, athletes with deep bradycardia do not present more arrhythmias and more hypotensive susceptibility than their non-bradycardic peers. Cardiac enlargement and autonomic alteration both seem to be involved in an athlete’s bradycardia.