Bradycardia in Athletes: Prevalence, Mechanisms, and Risks

Area of Science:

• Cardiology
• Sports Medicine
• Genetics

Background:

• Sinus bradycardia is common in endurance athletes, attributed to physiological adaptations.
• The genetic basis of athletic bradycardia remains largely unexplored.

Purpose of the Study:

• To investigate the genetic contribution to bradycardia in elite endurance athletes.
• To assess the association between a heart rate polygenic risk score (HR-PRS) and bradycardia in athletes.

Main Methods:

• Phenotyped 465 elite endurance athletes using cardiac imaging, exercise testing, and Holter monitoring.
• Assessed genetic susceptibility using a validated HR-PRS and compared athletes with non-athletes.
• Compared bradycardic athletes (BAs) with non-BAs.

Main Results:

• 38% of athletes exhibited minimum heart rates ≤40 bpm; 2% had HR ≤30 bpm.
• Lower HR-PRS was significantly associated with lower minimum heart rates and increased odds of resting bradycardia (OR, 2.2).
• Bradycardia and pauses were well-tolerated and not associated with adverse outcomes over 5.5 years.

Conclusions:

• Fitness and genetic variation contribute to sinus node function in endurance athletes.
• HR-PRS differs between athletes and non-athletes, suggesting a potential genetic determinant of athleticism.