Does Deep Bradycardia Increase the Risk of Arrhythmias and Syncope in Endurance Athletes?
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.
LTSI, Inserm UMR 1099, Rennes, F-35000.
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Matelot
Sport Medicine Department, University Hospital of Rennes, Rennes, France.
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Schnell
LTSI, Inserm UMR 1099, Rennes, F-35000.
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Khodor
Sport Medicine Department, University Hospital of Rennes, Rennes, France.
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Endjah
CIC-IT, Inserm Rennes 804, Rennes, F-35000.
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Kervio
LTSI, Inserm UMR 1099, Rennes, F-35000.
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Carrault
LTSI, Inserm UMR 1099, Rennes, F-35000.
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Thillaye du Boullay
Sport Medicine Department, University Hospital of Rennes, Rennes, France.
F
F
Carre
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000453:epidemiology*; D056352:Athletes; D001919:Bradycardia / Q000150:complications* / Q000209:etiology; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D011446:Prospective Studies; D057185:Sedentary Behavior; D013575:Syncope / Q000453:epidemiology*; D055815:Young Adult