Bradycardia in Athletes: Prevalence, Mechanisms, and Risks
Abstract
BACKGROUND: Sinus bradycardia is a well-recognized physiological adaptation in endurance athletes, primarily attributed to sinus node remodeling or increased vagal modulation. Although genetic influences on resting heart rate (HR) have been observed, the genetic contribution to athletic bradycardia has not been elucidated. METHODS: We phenotyped current and former elite endurance athletes in the Pro@Heart cohort study using multimodal cardiac imaging, cardiopulmonary exercise testing, and Holter monitoring. Genetic susceptibility to bradycardia was assessed using a validated HR-associated polygenic risk score (HR-PRS), in which lower scores are associated with a lower HR, and compared with healthy nonathletic controls. Clinical and genetic features of bradycardic endurance athletes with minimum HR ≤40 bpm on a Holter monitor (bradycardic athletes [BAs]) were compared with non-BAs). A healthy cohort of nonathletes from the ASPREE study (Aspirin in Reducing Events in the Elderly) were used for genetic comparisons. RESULTS: Among 465 endurance athletes (median age, 23 [18–49] years, 75% men), 175 (38%) had a minimum HR on a Holter monitor ≤40 bpm, of whom 7 (2% of total) had a HR ≤30bpm. Pauses ≥2 s were observed in 115 (25%) athletes, of whom 12 (3% of total) had pauses ≥3 s. Mobitz I second-degree atrioventricular block was observed in 15 (3% of total) athletes. BAs were younger and fitter and exhibited greater athletic cardiac remodeling than non-BAs. Mean HR-PRS was significantly lower in all athletes compared with ASPREE nonathletes ( P <0.001) and in BAs compared with non-BAs ( P =0.006). When the distribution of HR-PRS within our athletic cohort was considered, athletes with scores in the bottom quartile had a lower minimum HR (median HR, 41 [35–45] bpm versus 45 [40–49] bpm, P <0.001) and higher bradycardia burden (14 [2–37]% versus 2 [0%–25]%, P <0.001) than those with scores in the top quartile. After adjusting for age, sex, fitness, and indexed right atrial volume, HR-PRS was independently associated with lower minimum HR and increased the odds of resting bradycardia by 2-fold (odds ratio [OR], 2.2 [95% CI, 1.3–3.9]; P= 0.004). Neither bradycardia nor pauses were associated with increased risk of adverse outcomes over 5.5 years. CONCLUSIONS: Resting bradycardia (HR ≤40 bpm) and pauses of 2 to 3 s are present in a significant proportion of endurance athletes and are well tolerated. Our data suggest that both fitness and genetic variation contribute to sinus node function in endurance athletes. Intriguingly, HR-PRS differed between athletes and nonathletes, raising the possibility that genetics may be a determinant of athleticism.
Article Details
Authors (48)
Paolo D’Ambrosio
Jarne De Paepe
Department of Cardiology, Hartcentrum (R.P., J.D.P., Y.B., B.D., L.H., G.C.), Jessa Ziekenhuis, Hasselt, Belgium.
Luke W. Spencer
Department of Medicine, The University of Melbourne, Parkville, VIC, Australia (P.D., L.W.S., A.M.M., M.D.F., S.J.R., P.M.K., J.M.K., A.L.G.).
Monique Ohanian
Inherited Heart Diseases Lab (M.O., P.Y., M.S., R.J., D.F.), Darlinghurst, NSW, Australia
Kristel Janssens
Amy M. Mitchell
M. Darragh Flannery
Department of Medicine, The University of Melbourne, Parkville, VIC, Australia (P.D., L.W.S., A.M.M., M.D.F., S.J.R., P.M.K., J.M.K., A.L.G.).
Youri Bekhuis
Rik Pauwels
Department of Cardiology, Hartcentrum (R.P., J.D.P., Y.B., B.D., L.H., G.C.), Jessa Ziekenhuis, Hasselt, Belgium.
Boris Delpire
Department of Cardiology, Hartcentrum (R.P., J.D.P., Y.B., B.D., L.H., G.C.), Jessa Ziekenhuis, Hasselt, Belgium.
Christophe Dausin
Department of Movement Sciences (C.D.), Katholieke Universiteit Leuven, Belgium.
Stephanie J. Rowe
Department of Medicine, The University of Melbourne, Parkville, VIC, Australia (P.D., L.W.S., A.M.M., M.D.F., S.J.R., P.M.K., J.M.K., A.L.G.).
Tim Van Puyvelde
Departments of Cardiovascular Sciences (J.D.P., Y.B., R.P., B.D., T.V.P., T.R., R.W., G.C.), KU Leuven, Leuven, Belgium.
Paul E. Young
Inherited Heart Diseases Lab (M.O., P.Y., M.S., R.J., D.F.), Darlinghurst, NSW, Australia
Magdalena J. Soka
Inherited Heart Diseases Lab (M.O., P.Y., M.S., R.J., D.F.), Darlinghurst, NSW, Australia
Renee Johnson
Inherited Heart Diseases Lab (M.O., P.Y., M.S., R.J., D.F.), Darlinghurst, NSW, Australia
Chenglong Yu
Beijing National Laboratory for Molecular Sciences, CAS Laboratory of Colloid and Interface and Thermodynamics, CAS Research/Education Center for Excellence in Molecular Sciences, Center for Carbon Neutral Chemistry, Institute of Chemistry
Gwilym M. Morris
Department of Cardiology, John Hunter Hospital, New Lambton Heights, NSW, Australia (P.D., G.M.M.).
Tomas Robyns
Department of Cardiovascular Sciences (R.P., R.D.B., J.D.P., Y.B., B.D., P.S., T.K., T.R., R.W., G.C.), Katholieke Universiteit Leuven, Belgium.
Paul Lacaze
Eleni Giannoulatou
Peter M. Kistler
Department of Medicine, The University of Melbourne, Parkville, VIC, Australia (P.D., L.W.S., A.M.M., M.D.F., S.J.R., P.M.K., J.M.K., A.L.G.).
Jonathan M. Kalman
Department of Medicine, The University of Melbourne, Parkville, VIC, Australia (P.D., L.W.S., A.M.M., M.D.F., S.J.R., P.M.K., J.M.K., A.L.G.).
Hein Heidbüchel
University Hospital Antwerp, Antwerp, Belgium
Rik Willems
Department of Cardiovascular Sciences (R.P., R.D.B., J.D.P., Y.B., B.D., P.S., T.K., T.R., R.W., G.C.), Katholieke Universiteit Leuven, Belgium.
Guido Claessen
Diane Fatkin
André La Gerche
Heart, Exercise and Research Trials Laboratory, Saint Vincent’s Institute of Medical Research, Melbourne, Australia (A.L.G.).
Sofie Van Soest
Lieven Herbots
Faculty of Medicine and Life Sciences, Limburg Clinical Research Center, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium (S.D., S.M.F., P.K., E.M., K.T., S.D., L.H., W.M., J.V., P.B.B.).
Jan Bogaert
Peter Hespel
Steven Dymarkowski
Department of Radiology (S.D.), University Hospitals Leuven, Belgium.
Tom Dresselaers
Hielko Miljoen
Kasper Favere
Bernard Paelinck
Dorien Vermeulen
Isabel Witvrouwen
Dominique Hansen
Bert Op’t Eijnde
Daisy Thijs
Peter Vanvoorden
Kristof Lefebvre
Thomas Rosseel
Elizabeth Paratz
Maria J. Brosnan
David L. Prior