The effect of exercise and heart rate on fibrinolytic activity

The effect of heart rate on plasma fibrinolytic activity was investigated in nine patients with dual chamber cardiac pacemakers before and after 10 min of stimulated tachycardia to 123 beats/min. The results were compared to seven volunteers who performed submaximal exercise to 90% target heart rate and to five of the seven who underwent a second period of exercise to a heart rate of 120 beats/min. During submaximal exercise (mean heart rate 152 beats/min) the median ECLT fell from 248 min (interquartile range 147.5-305) to 90 (55-202) P less than 0.01 and t-PA:Ag increased from 6.1 ng/ml (3.92-7.95) to 9.3 (8.45-12.7), P less than 0.025. PAI and PAI-1:Ag fell from 12.0 IU/ml (5.85-15.5) to 4.1 (1.85-11.67), P less than 0.01, and 9.7 ng/ml (2.8-10.6) to 6.7 (2.1-9.9), P less than 0.01 respectively. A lower level of exercise to 120 beats/min resulted in a reduction in ECLT from 215 min (167.5-228.5) to 135 (116-154), P = 0.05 and an increase in t-PA:Ag from 4 ng/ml (3.07-4.45) to 5.0 (3.3-5.22) P less than 0.05. PAI and PAI-1:Ag fell from 7.6 IU/ml (3.27-8.5) to 7.1 (2.77-7.4) and from 7.7 ng/ml (6.0-7.92) to 6.4 (4.8-7.3) respectively but these changes were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)