von Willebrand factor, ADAMTS-13, and thrombospondin 1 in relation to clinical outcomes in elderly patients with a recent myocardial infarction.

Background: von Willebrand factor (VWF) multimers are cleaved by A disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS-13) into less active fragments. Thrombospondin 1 (TSP-1) competes with VWF's cleavage site, protecting it from degradation. Low ADAMTS-13 and high VWF have been associated with cardiovascular disease and atrial fibrillation (AF). Objectives: We aimed to investigate whether VWF, ADAMTS-13, and TSP-1 are associated with clinical outcome. Methods: Elderly patients with a recent myocardial infarction (MI) (n = 1027) were followed for 2 years. Blood was collected 2 to 8 weeks after the MI for ADAMTS-13, VWF, and TSP-1 measures. The primary endpoints (major adverse cardiovascular events; n = 210) included the first event of MI, stroke, heart failure hospitalization, coronary revascularization, and all-cause death. Total mortality was also registered (n = 56). The secondary endpoint was new-onset AF (n = 43). Results: Concentrations of VWF, ADAMTS-13, and TSP-1 did not intercorrelate. The risk of major adverse cardiovascular events was altered in patients with VWF ≥ median (hazard ratio [HR], 1.4; 95% CI, 1.0-1.8; P = .03) and ADAMTS-13 ≥ median (HR, 0.7; 95% CI, 0.5-0.9; P = .02); however, it was not significant in adjusted models. VWF and ADAMTS-13 were significantly associated with total mortality, with a HR of 2.7 (95% CI, 1.6-4.6; P < .001) for VWF (Q4 vs. Q1-Q3) and HR of 0.3 (95% CI, 0.2-0.5; P < .001) for ADAMTS-13 (Q2-4 vs. Q1). The associations persisted in multivariable analysis, but the significance disappeared for VWF after correcting for high-sensitivity C-reactive protein. The risk of new-onset AF was lower in patients with VWF ≥ median (HR, 0.5; 95% CI, 0.3-1.0; P = .04]), and this was still significant after adjustments. Conclusion: Although low ADAMTS-13 predicted death, the cardiovascular risk associated with VWF and ADAMTS-13 was weaker than previously reported. Low VWF is associated with new-onset AF and needs further research.

Genetic Variation in ADAMTS13 is Related to VWF Levels, Atrial Fibrillation and Cerebral Ischemic Events.

INTRODUCTION: ADAMTS13 cleaves von Willebrand factor (VWF) multimers into less active fragments. Both markers have been related to cardiovascular disease (CVD). We aimed to investigate the influence of ADAMTS13 single nucleotide polymorphisms (SNPs) on levels of ADAMTS13 and VWF, and CVD. METHODS: The c.1342C>G, g.41635A>G and c.2699C>T polymorphisms were determined in patients with chronic coronary syndrome (n = 1000). VWF and ADAMTS13 were analyzed. Clinical endpoints after 2 years (n = 106) were unstable angina pectoris, myocardial infarction, non-hemorrhagic stroke and death. RESULTS: The SNPs did not affect ADAMTS13 levels. The 41635A-allele associated with higher VWF levels (P < .001). Patients with the 1342G-allele had significantly higher frequency of previous atrial fibrillation (n = 26, P = .016) and cerebral ischemic events (n = 47, P = .030). Heterozygous of the 1342CG variant experienced more clinical endpoints compared to homozygous (CC and GG) (P = .028). CONCLUSION: The association between the 41635A-allele and VWF indicates a role for this polymorphism in VWF regulation. ADAMTS13 has previously been linked to atrial fibrillation and ischemic stroke, and our findings suggest that the 1342G-allele may be of significance. The association between the 1342CG genotype and endpoints needs further investigations.Clinicaltrials.gov, ASCET, NCT00222261. https://clinicaltrials.gov/ct2/show/NCT00222261?term=NCT00222261&draw=2&rank=1.

A brief review on resistance to P2Y12 receptor antagonism in coronary artery disease.

BACKGROUND: Platelet inhibition is important for patients with coronary artery disease. When dual antiplatelet therapy (DAPT) is required, a P2Y12-antagonist is usually recommended in addition to standard aspirin therapy. The most used P2Y12-antagonists are clopidogrel, prasugrel and ticagrelor. Despite DAPT, some patients experience adverse cardiovascular events, and insufficient platelet inhibition has been suggested as a possible cause. In the present review we have performed a literature search on prevalence, mechanisms and clinical implications of resistance to P2Y12 inhibitors. METHODS: The PubMed database was searched for relevant papers and 11 meta-analyses were included. P2Y12 resistance is measured by stimulating platelets with ADP ex vivo and the most used assays are vasodilator stimulated phosphoprotein (VASP), Multiplate, VerifyNow (VN) and light transmission aggregometry (LTA). DISCUSSION/CONCLUSION: The frequency of high platelet reactivity (HPR) during clopidogrel therapy is predicted to be 30%. Genetic polymorphisms and drug-drug interactions are discussed to explain a significant part of this inter-individual variation. HPR during prasugrel and ticagrelor treatment is estimated to be 3-15% and 0-3%, respectively. This lower frequency is explained by less complicated and more efficient generation of the active metabolite compared to clopidogrel. Meta-analyses do show a positive effect of adjusting standard clopidogrel treatment based on platelet function testing. Despite this, personalized therapy is not recommended because no large-scale RCT have shown any clinical benefit. For patients on prasugrel and ticagrelor, platelet function testing is not recommended due to low occurrence of HPR.

vWF/ADAMTS13 is associated with on-aspirin residual platelet reactivity and clinical outcome in patients with stable coronary artery disease.

BACKGROUND: The mechanisms behind residual platelet reactivity (RPR) despite aspirin treatment are not established. It has been shown that coronary artery disease (CAD) patients with high on-aspirin RPR have elevated levels of von Willebrand factor (vWF). ADAMTS13 is a metalloprotease cleaving ultra large vWF multimers into less active fragments.Our aim was to investigate whether ADAMTS13 and vWF/ADAMTS13 ratio were associated with high RPR, and further with clinical endpoints after 2 years. METHODS: Stable aspirin-treated CAD patients (n = 999) from the ASCET trial. RPR was assessed by PFA-100. ADAMTS13 antigen and activity were analysed using chromogenic assays. Endpoints were a composite of acute myocardial infarction, stroke and death. RESULTS: The number of patients with high RPR was 258 (25.8%). Their serum thromboxane B2 (TxB2) levels were low, indicating inhibition of COX-1. They had significantly lower levels of ADAMTS13 antigen compared to patients with low RPR (517 vs 544 ng/mL, p = 0.001) and significantly lower ADAMTS13 activity (0.99 vs 1.04 IU/mL, p = 0.020). The differences were more pronounced when relating RPR to ratios of vWF/ADAMTS13 antigen and vWF/ADAMTS13 activity (p < 0.001, both). We found an inverse correlation between vWF and ADAMTS13 antigen (r = -0.14, p < 0.001) and ADAMTS13 activity (r = -0.11, p < 0.001). No correlations between TxB2 and ADAMTS13 antigen or activity, were observed, implying that ADAMTS13 is not involved in TxB2 production. Patients who experienced endpoints (n = 73) had higher vWF level (113 vs 105%, p = 0.032) and vWF/ADAMTS13 antigen ratio (0.23 vs 0.20, p = 0.012) compared to patients without. When dichotomizing vWF/ADAMTS13 antigen at median level we observed that patients above median had higher risk for suffering endpoints, with an adjusted OR of 1.86 (95% CI 1.45, 2.82). CONCLUSION: These results indicate that ADAMTS13 is of importance for RPR, and that it in combination with vWF also is associated with clinical endpoints in stable CAD patients on aspirin. TRIAL REGISTRATION: Clinicaltrials.gov NCT00222261. Registered 13.09.2005. Retrospectively registered.