Introduction: Increased plasma levels of von Willebrand factor (VWF) have been reported in acute myocardial infarction (AMI). Recently, we showed reduced activity of a VWF-cleaving protease (ADAMTS13) in AMI patients. However, there is no information as to whether ADAMTS13 affects the pathogenesis of unstable angina (UA). Thus, the purpose of this study was to examine changes in plasma VWF and ADAMTS13 levels in UA patients.
Materials and methods: Plasma VWF and ADAMTS13 levels (mU/ml) were measured in 45 patients with UA, 55 with stable exertional angina (SEA) and 47 with chest pain syndrome (CPS) at the time of coronary angiography. Levels were also measured in 15 UA patients after 6 months of follow-up.
Results: VWF antigen levels (mU/ml) increased significantly in UA patients compared with SEA or CPS (2129.3+/-739.5, 1571.8+/-494.2 and 1569.5+/-487.0, respectively; P < 0.0001 in UA vs. SEA or CPS). ADAMTS13 antigen levels (mU/ml) were significantly lower in UA patients than SEA or CPS (737.3+/-149.5, 875.3+/-229.0 and 867.7+/-195.5, respectively; P < 0.01 in UA vs. SEA or CPS). Furthermore, there was a significant inverse correlation between VWF and ADAMTS13 antigen levels (r = -0.302, P = 0.0002). The antigen levels at 6 months of follow-up were not different compared to the acute phase in the 15 UA patients that had repeated blood sampling.
Conclusions: These findings suggest that there is prolonged thrombogenicity in UA patients represented as an imbalance between VWF and ADAMTS13 activity.