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Comparative behaviour of the components of the factor VIII complex in acute myocardial infarction
Insights
Patients with acute myocardial infarction (AMI) show elevated levels of factor VIII related antigen (VIII R:Ag) and von Willebrand factor (VIII R:WF). The ratio of VIII R:Ag to VIII R:WF increases significantly during AMI, suggesting altered factor VIII complex regulation.
Area of Science:
- Cardiology
- Hematology
- Biochemistry
Background:
- The factor VIII complex, comprising VIII coagulant (VIII:C), VIII related antigen (VIII R:Ag), and von Willebrand factor (VIII R:WF), plays a crucial role in hemostasis.
- Alterations in factor VIII components have been implicated in various cardiovascular conditions.
Purpose of the Study:
- To investigate the levels and ratios of factor VIII complex components in patients experiencing acute myocardial infarction (AMI).
- To explore the potential role of acute phase reactions and endothelial injury in modifying factor VIII complex composition during AMI.
Main Methods:
- Standardized assays were employed to measure VIII R:WF, VIII R:Ag, and VIII:C in 32 AMI patients and 19 control subjects.
- Serial measurements were performed in a subset of 7 severe AMI patients to assess changes over time.
Main Results:
- Significantly elevated VIII R:WF levels were observed in AMI patients compared to controls.
- VIII R:Ag levels increased to a greater extent than VIII R:WF, leading to an elevated VIII R:Ag/VIII R:WF ratio (1.58 in patients vs. 1.21 in controls).
- Similar increases in the VIII R:Ag/VIII:C ratio were noted, and plasma levels of VIII R:Ag and VIII R:WF decreased within a week post-AMI, though the ratio remained altered.
Conclusions:
- Acute myocardial infarction is associated with significant changes in the factor VIII complex, characterized by disproportionate increases in VIII R:Ag relative to VIII R:WF.
- These alterations may be attributed to acute phase responses and endothelial damage, potentially releasing less polymerized von Willebrand factor multimers.
Abstract:
The three components of the factor VIII complex: VIII coagulant (VIII:C), VIII related antigen (VIII R:Ag) and the VIII related von Willebrand factor (VIII R:WF) were studied in patients with acute myocardial infarction (AMI). Using a carefully standardized technique for the determination of VIII R:WF, a significantly higher R:WF level was found in 32 patients compared to 19 control subjects, confirming our previous results. However VIII R:AG was increased to an even greater extent, resulting in a VIII R:Ag/VIII R:WF ratio of 1.58 +/- 0.084 in patients, compared to 1.21 +/- 0.045 in controls. A similar increase of the VIII R:AG/VIII:C ratio was noted in the 13 patients in whom VIII:C was investigated. In 7 patients with severe AMI who could be investigated twice the plasma levels of both VIII R:Ag and VIII R:WF were found to be lower a week after the acute event than during the first 48 hours. However the VIII R:Ag/VIII R:WF ratio was not significantly reduced after 7 days. Acute phase reaction and endothelial injury resulting in release of multimers which are less polymerised are probably involved in the above changes.