Abstract Background Atrial fibrillation (AF) is more prevalent among endurance-trained athletes when compared to non-athletes. The underlying pathophysiology and mechanisms for this phenomenon remain unknown but repeated exposure to an exaggerated blood pressure (BP) response during exercise may contribute to the development of AF in this population. Purpose We aimed to assess whether endurance athletes with AF have a higher maximal systolic BP (SBP) or a higher BP relative to exercise intensity compared to endurance athletes without AF. Methods Endurance athletes with paroxysmal AF (n=66, 96% male) from the ProAFHeart, NEXAF Detraining and Master@Heart studies were matched for age and sex to endurance athletes without AF (n=66, 96% male). Participants with a history of hypertension were excluded. All athletes underwent a maximal graded cardiopulmonary exercise test on a cycle ergometer to assess exercise BP using an automated auscultatory BP machine, maximal oxygen uptake (VO2peak) and peak workload. All athletes were in sinus rhythm at the time of testing and BP was measured pre-exercise seated on the bike and every 2 min throughout the test. Exercise BP measurements included the maximum exercise SBP (SBPmax) and the slopes of the relationships between SBP, diastolic BP (DBP) and workload (W) as determined from linear regression analysis (SBP/W-slope and DBP/W-slope, respectively). The resting SBP and DBP were measured in the supine position after 10min of rest. Independent T-test (parametric data) or the Mann-Whitney U-test (non-parametric data) assessed for the differences between the two groups. Results The 66 athletes with AF were of similar age and sex as the 66 athletes without AF, median age (55 [IQR 45, 61] vs 54 [IQR 44, 62] years, p=0.839), 4% female. There was no difference in (mean±SD) VO2peak (46 ±9 vs 49±10 mL/kg/min, p=0.114) and peak workload (365±67 vs 385±83 W, p=0.136), nor resting SBP (131±13 vs 128±13 mmHg, p=0.169) and resting DBP (76±9 vs 75±11 mmHg, p=0.465) between athletes with and without AF respectively (Table 1). Athletes with AF showed no significant difference to athletes without AF for exercise BP responses (Figure 1) including SBPmax (222±22 vs 219±28 mmHg, p=0.479), SBP/W-slope (0.22±0.07 vs 0.24±0.08 mmHg/W, p=0.310) and median DBP/W-slope (-0.01 [IQR -0.02, 0.01] vs -0.01 [IQR -0.03, 0.02] mmHg/W, p=0.703). Conclusion When comparing endurance athletes with and without paroxysmal AF, there were no differences in the maximal BP attained during exercise or in their BP response indexed to external workload (SBP/W-slope) suggesting that exercise-induced hypertension does not explain the athletic predisposition to AF.
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