Altitude and the development of atrial fibrillation in high endurance athletes
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Abstract
INTRODUCTION: Atrial fibrillation (AF) stands as the predominant cardiac arrhythmia in the United States, carrying substantial morbidity and mortality implications. While exercise typically offers cardiovascular benefits, rigorous endurance activities, especially at high altitudes, might paradoxically heighten AF risk due to increased cardiovascular strain and remodeling. This study aims to investigate whether a significant association exists between high-altitude endurance training (>1500m) and AF incidence compared to training at sea level in high performance athletes.
REVIEW OF THE LITERATURE: Atrial fibrillation (AF) is a prevalent arrhythmia characterized by atrial fibrosis, inflammation, and physiological stressors like exercise and altitude exposure. Recent studies emphasize atrial fibrosis as pivotal in AF development, marked by altered conduction velocities and re-entry circuit facilitation. Inflammatory markers such as CRP and fibrinogen correlate with AF onset and recurrence. While moderate exercise mitigates cardiovascular risk factors and inflammation, high-volume endurance exercise can increase AF risk, particularly in middle-aged male athletes. Altitude exposure poses additional challenges, potentially exacerbating AF risk via pulmonary hypertension, right heart strain, and hypoxia-induced inflammatory responses. Chronic hypoxia adaptations, including heightened sympathetic tone and pro-fibrotic pathways, may further predispose individuals to AF, especially when coupled with intense endurance training.
METHODS: This study adopts a paired case-control design to examine the association between AF in high-performance athletes and altitude training. Participants from Massachusetts and Colorado sports centers will be grouped by altitude exposure (>1500m vs. sea level). Using Strava data, exercise metrics (speed, duration, elevation) will be analyzed to calculate average weekly metabolic equivalents (MET-h). Statistical analyses will assess AF prevalence relative to altitude exposure, employing descriptive methods to visualize dose-response trends.
CONCLUSION: Despite its rising popularity among elite athletes, high-altitude training lacks comprehensive evidence of benefits and potential cardiovascular risks, notably AF. As global participation in endurance sports increases, understanding AF prevalence in athletes training at high altitudes is crucial for shaping long-term cardiovascular health guidelines.
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2024