Fibrinolytic response to acute exercise in patients with peripheral arterial disease

Purpose: Elevations in tissue plasminogen activator (rPA) are postulated to protect against atherothrombotic events during exercise. However, fibrinol ytic response to repetitive bouts of symptom-limited exercise is unknown in peripheral arterial disease (PAD) patients, a population with impaired fib rinolysis and increased risk for ischemic events. The purpose of the presen t study was to evaluate the fibrinolytic response to repetitive bouts of sy mptom-limited exercise in PAD patients. Methods: Nine (8 male, 1 female) pa tients with Fontaine State II PAD were studied. Easting blood samples for d etermination of tPA and plasminogen activator inhibitor (PAI-1) were obtain ed into an acidified citrate solution via an indwelling venous catheter bef ore, immediately after, 30 min after, and 60 min after submaximal treadmill walking. Patients walked intermittently at 65% of maximal intensity achiev ed on a previous graded exercise test until 30 min of exercise was achieved . Results: Exercise increased tPA activity by 180% (0.5 +/- 0.16 IU.mL(-1) baseline, 1.4 +/- 1.2 IU.mL(-1) postexercise), and decreased PAI-1 activity by 40% (20.6 +/- 5.5 AU.mL(-1) baseline, 11.8 +/- 6.2 AU.mL(-1) postexerci se), without changing rPA or PAI-I antigen. Notably, plasma tPA activity le vels 1 h after exercise remained elevated by 80%, whereas PAI-I activity re mained decreased by 49%. The decrease in PAI-1 significantly (P < 0.05) cor related with oxygen uptake ((V) over dotO(2)) during submaximal exercise (r = -0.77). Conclusion: These findings demonstrate that repetitive bouts of symptom-limited exercise produce a substantial improvement in the fibrinoly tic profile of PAD patients, which persists at least 1 h after exercise ces sation.