Association between heart rate recovery after exercise testing and plasminogen activator inhibitor 1, tissue plasminogen activator, and fibrinogen in apparently healthy men

Objective: Delayed heart rate recovery (HRR) following exercise testing, an indicator of decreased autonomic nervous system activity, is associated with an increased risk of cardiovascular events. Because autonomic nervous system function may be associated with fibrinolytic factors, we tested the hypothesis that delayed HRR is associated with elevated fibrinolytic factors. Methods: In 547 (mean age 49.4 ± 6.9 years) healthy men who underwent exercise treadmill testing and fasting blood analysis for fibrinolytic factors, we calculated HRR as the difference between maximum heart rate during the test and heart rate 1 min after cessation of exercise. Results: HRR was inversely correlated with plasminogen activator inhibitor 1 (PAI-1) activity (r = -0.23, p < 0.001), tissue plasminogen activator (t-PA) antigen (r = -0.19, p < 0.001), and fibrinogen (r = -0.11, p < 0.05). Men in the lowest quartile of HRR had significantly higher PAI-1, t-PA, and fibrinogen than men in the highest quartile of HRR (all p trend <0.001). HRR was independently associated with PAI-1 (β = -0.12, p < 0.01) and fibrinogen (β = -0.09, p = 0.04) but not t-PA (β = -0.06, p = 0.29) in a multiple regression analysis. Conclusions: These results suggest that delayed HRR after exercise testing is associated with elevated fibrinolytic factors in cross-section. The presence of other CHD risk factors does not explain this association, but further research is needed to identify the direction of the association.