Int J Sports Med 2016; 37(10): 792-798
DOI: 10.1055/s-0035-1569348
Physiology & Biochemistry
© Georg Thieme Verlag KG Stuttgart · New York

Does Deep Bradycardia Increase the Risk of Arrhythmias and Syncope in Endurance Athletes?

D. Matelot
1  LTSI, Inserm UMR 1099, Rennes, F-35000
,
F. Schnell
2  Sport Medicine Department, University Hospital of Rennes, Rennes, France
,
N. Khodor
1  LTSI, Inserm UMR 1099, Rennes, F-35000
,
N. Endjah
2  Sport Medicine Department, University Hospital of Rennes, Rennes, France
,
G. Kervio
3  CIC-IT, Inserm Rennes 804, Rennes, F-35000
,
G. Carrault
1  LTSI, Inserm UMR 1099, Rennes, F-35000
,
N. Thillaye du Boullay
1  LTSI, Inserm UMR 1099, Rennes, F-35000
,
F. Carre
2  Sport Medicine Department, University Hospital of Rennes, Rennes, France
› Author Affiliations
Further Information

Publication History



accepted after revision 30 November 2015

Publication Date:
10 June 2016 (online)

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.