Fibrinolytic response to acute exercise in patients with peripheral arterial disease.

Abstract

Elevations in tissue plasminogen activator (tPA) are postulated to protect against atherothrombotic events during exercise. However, fibrinolytic response to repetitive bouts of symptom-limited exercise is unknown in peripheral arterial disease (PAD) patients, a population with impaired fibrinolysis and increased risk for ischemic events. The purpose of the present study was to evaluate the fibrinolytic response to repetitive bouts of symptom-limited exercise in PAD patients. Nine (8 male, 1 female) patients with Fontaine State II PAD were studied. Fasting blood samples for determination of tPA and plasminogen activator inhibitor (PAI-1) were obtained into an acidified citrate solution via an indwelling venous catheter before, immediately after, 30 min after, and 60 min after submaximal treadmill walking. Patients walked intermittently at 65% of maximal intensity achieved on a previous graded exercise test until 30 min of exercise was achieved. 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) postexercise), without changing tPA or PAI-1 antigen. Notably, plasma tPA activity levels 1 h after exercise remained elevated by 80%, whereas PAI-1 activity remained decreased by 49%. The decrease in PAI-1 significantly (P < 0.05) correlated with oxygen uptake (VO(2)) during submaximal exercise (r = -0.77). These findings demonstrate that repetitive bouts of symptom-limited exercise produce a substantial improvement in the fibrinolytic profile of PAD patients, which persists at least 1 h after exercise cessation.