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ALTERED ULTRALARGE VON WILLEBRAND FACTOR LEVELS AND ADAMTS-13 ACTIVITY AFFECT RESIDUAL PLATELET REACTIVITY IN HIGH RISK VASCULAR PATIENTS ON DUAL ANTIPLATELET THERAPY

Abstract number: P-W-362

Marcucci¹ R., Cesari¹ F., Cinotti² S., Gori¹ A., Paniccia¹ R., Gensini³ G., Abbate¹ R.

¹¹Surgical and Medical Critical Area, University of Florence ²²Centro Coagulopatie Congenite, AOU Careggi ³³Don CArlo Gnocchi Foundation, Unversity of Florence, Florence, Italy

How-to-cite Marcucci R, Cesari F, Cinotti S, Gori A, Paniccia R, Gensini G, Abbate R. ALTERED ULTRALARGE VON WILLEBRAND FACTOR LEVELS AND ADAMTS-13 ACTIVITY AFFECT RESIDUAL PLATELET REACTIVITY IN HIGH RISK VASCULAR PATIENTS ON DUAL ANTIPLATELET THERAPY. J Thromb Haemost 2007; 5 Supplement 2: P-W-362

Abstract

Introduction: We have hypothesized the presence of ultralarge vWF eventually accompanied by a reduced activity of ADAMTS-13 as one of the mechanisms of residual platelet reactivity (RPR).

Methods: We investigated 159 patients with acute coronary syndromes on dual antiplatelet therapy. Platelet function was assessed by optical aggregometry on platelet-rich-plasma induced by arachidonic acid (AA-PA) and 10 micromol/L ADP (ADP-PA). RPR was defined in the presence of AA-PA >20% and/or ADP-PA >70%. vWF levels and collagen binding assay (CBA) were measured by a conventional ELISA system. ADAMTS-13 antigen levels and activity were measured by a fluorogenic assay (Technozym ADAMTS-13, Technoclone).

Results: 64/159 patients had RPR by AA-PA (40.2%), 36/159 had RPR by ADP-PA (22.6%)and 25/159 (15.7%) by both AA-PA and ADP-PA (dual RPR. Patients with RPR by AA-PA and by ADP-PA had significantly higher levels of both vWF antigen levels and CBA [vWF: 327%(108-780) vs 200 (74-854), p<0.0001; CBA: 271%(7.5-934) vs 195%(21-978), p<0.0001/vWF: 330%(145-645) vs 227 (74-854,p=0.01); CBA: 235%(12.5-828) vs 211%(7.5-978),p<0.05]. Also patients with dual RPR were found to have significantly higher levels of vWF antigen and CBA: vWF= 339%(159-645) vs 226 (74-854), p<0.0001; CBA= 295%(12.5-828) vs 212.5%(7.5-978),p<0.05. A significantly decreased ADAMTS-13 activity was demonstrated in patients with RPR induced by AA-PA (82.1% (24.7-129.8) vs 93.1%(10.3-172.7), p<0.005), by ADP-PA (78.4%(52.8-137.7) vs 90.7% (10.3-172.7), p<0.05) and in patients with dual RPR (76.3%(52.8-117.3) vs 90.6%(10.3-172.7), p<0.05). No significant differences were found in ADAMTS-13 antigen levels.

Conclusions: These results demonstrate that platelet function in response to antiplatelet therapy might be modulated by the presence of significantly higher levels of CBA. One of the possible mechanisms explaining the presence of these forms of vWF, in addition to the endothelial activation, is the presence of reduced levels of ADAMTS-13.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

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