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[Changes induced by venous occlusion in coagulation and fibrinolysis in patients with old myocardial infarction]
T Suzuki1, K Yamauchi, Y Yamada
1First Department of Internal Medicine, Nagoya University School of Medicine.
Insights
Patients with myocardial infarction exhibit hypercoagulability and hypofibrinolysis, particularly those with diabetes. Impaired vascular endothelial function is linked to elevated PAI-1 and alpha 2 PI levels, affecting tissue plasminogen activator (t-PA) activity.
Area of Science:
- Cardiovascular Medicine
- Hematology
- Endocrinology
Context:
- Assessing vascular endothelial function in patients post-myocardial infarction (MI) is crucial for understanding thrombotic risk.
- Previous research indicates altered hemostatic and fibrinolytic profiles in cardiovascular disease patients.
Purpose:
- To evaluate vascular endothelial function by measuring hemostatic and fibrinolytic parameters before and after venous occlusion in MI patients and healthy controls.
- To identify specific markers associated with hypercoagulability and hypofibrinolysis in MI patients, especially those with comorbid diabetes mellitus.
Summary:
- Venous occlusion revealed significantly lower tissue plasminogen activator (t-PA) activity post-occlusion in MI patients compared to controls, most pronounced in those with diabetes.
- Elevated plasminogen activator inhibitor-1 (PAI-1) and alpha 2-plasmin inhibitor (alpha 2 PI) levels were observed in MI patients, contributing to reduced t-PA activity.
- Pre-occlusion levels of t-PA antigen and Factor VIII related antigen (VIII R: Ag) were higher in MI patients, but release upon occlusion was similar to controls, suggesting a baseline hypercoagulable and hypofibrinolytic state.
Impact:
- Findings suggest that MI patients, particularly those with diabetes, are in a prothrombotic state characterized by impaired fibrinolysis.
- The study highlights the role of PAI-1 and alpha 2 PI in modulating t-PA activity and endothelial function in this patient population.
- These insights can inform the development of targeted therapeutic strategies to mitigate thrombotic events in post-MI patients.
Abstract:
The levels of hemostatic and fibrinolytic parameters and of molecular markers in venous blood before and after 10 minutes of venous occlusion were measured to evaluate vascular endothelial function in 36 patients with old myocardial infarction, and also in 20 healthy subjects. T-PA activity in the venous blood after occlusion was significantly lower in the patient group compared with the control group, and was lowest in patients with diabetes mellitus. These results were considered to be attributable to elevated PAI-1 and alpha 2 PI levels in these patients. The mean levels of t-PA antigen and VIII R: Ag in venous blood before occlusion were significantly higher in the patient group, but the mean amount of release was no higher in patients than in controls. The plasmin.alpha 2PI complex levels before venous occlusion seemed to indicate the presence of secondary fibrinolysis accompanying hypercoagulability, and the level was significantly higher in patients with diabetes mellitus. Venous occlusion induced the release of t-PA and VIII R: Ag without causing a significant difference in the mean amount of increase of these substances in patient and control groups. However, the lower level of t-PA activity after venous occlusion together with the higher levels of VIII: C, VIII R: Ag, alpha 2PI, PAI-1, and plasmin.alpha 2PI complex before venous occlusion in the patients, indicated that the patient group was in a hypercoagulable and hypofibrinolytic state. In those with diabetes mellitus, the changes were more significant.