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Purpose: To determine the time point at which thrombocytopenia after TAVI procedure is an indicator of the worst prognosis, with special consideration of perioperative platelet and coagulation activation as its potential causes., Methods: Thirty two patients (mean age 78.5±7.9years, 62% females) qualified for TAVI procedure were prospectively evaluated. Platelet counts were assessed at baseline and for the next three postoperative (POD) days. Platelet activation was evaluated by P-selectin (PS, serum, ELISA) and platelet factor 4 (PF-4, CTAD plasma), and blood coagulation activation by prothrombin fragments 1+2 (F1+2, plasma, ELISA). Composite end point (CEP) including death and the need of cardiovascular rehospitalization was assessed after a mean of 14.1±6.7months., Results: During the follow up period half of the patients reached CEP. Thrombocytopenia was more profound and frequent in patients with CEP as compared to those without (p<0.05). No differences regarding either the biomarkers of platelet (PS, PF-4) or coagulation (F1+F2) activation between the groups with and without CEP were found. Patients with moderate-to-severe thrombocytopenia at baseline had worse prognosis (log-rank test, p=0.0003). Based on the receiver operating characteristic curve analysis, the differences between platelet count on each postoperative day and the baseline count did not have any predictive value in CEP occurrence., Conclusions: Patients with thrombocytopenia following TAVI procedure have poor prognosis, however, the changes on the particular days are not more important than initial platelet count. Further studies are needed to evaluate platelet and blood coagulation activation as potential causes of thrombocytopenia and impaired prognosis related to it., (Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.)

Thrombocytopenia (TP) following transcatheter aortic valve implantation (TAVI) procedure is a common phenomenon but the underlying mechanisms are neither well known nor described. Postinterventional severe TP is related to worse early and late outcome. Moreover, the statement of enhanced platelet and coagulation activation might justify even stronger antiplatelet and anticoagulation therapy following TAVI procedure. Thus, the examination of the pathomechanisms responsible for TP post TAVI seems to be crucial. Several hypotheses have been raised. TP can be caused by insufficient production or impaired platelet renewal. On the other hand, increased platelet activation, consumption and destruction might also be responsible for TP. These findings, mostly related to the procedure alone, need further investigation. Here, we summarize the potential multifactorial causes of post TAVI thrombocytopenia., (Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.)

Introduction: Even though thrombocytopenia following transcatheter aortic valve implantation (TAVI) has been described, further investigation of this phenomenon is needed., Aims: To determine which factors may explain the fall in platelet count that occurs after implantation of a TAVI device, including markers of platelet and blood coagulation activation., Material and Methods: 32 patients without previous indications for dual antiplatelet therapy (mean age 78.5±7.9 years, 62% females) with severe aortic valve stenosis (mean gradient 54.6±16.9mmHg) who qualified for TAVI procedure (Edwards Sapien XT) were prospectively analyzed. Platelet counts were analyzed before the surgery, on the day of the procedure and for the three following postoperative days (POD 1 to 3). To assess platelet activation P-selectin (PS, serum) and platelet factor 4 (PF-4, CTAD plasma) were measured, whereas for the evaluation of coagulation activation prothrombin fragments 1+2 (F1+2, plasma) were assessed before the procedure, on POD-1 and POD-3 (ELISA)., Results: During the postoperative period a significant platelet count drop, the most evident on POD-2, was observed followed by a platelet count raise. The platelet count drop correlated directly with the amount of iodinated contrast agent (r=0.42, p=0.016) and inversely with baseline mean platelet volume (r=-0.37, p=0.046). Neither clinical nor perioperative parameters, except contrast medium, influenced platelet count decrease. No significant differences regarding the concentration of the evaluated markers in patients with and without thrombocytopenia were found. PF-4 and F1+2 significantly changed during the study (p<0.05). Greater acute PF-4 decrease correlated with greater acute platelet count drop (r=0.48, p=0.043), and during the study slower PF-4 increase correlated with higher platelet count increase on POD-3 (r=-0.505, p=0.032). Lower baseline PS correlated with lower baseline platelet count and higher platelet count increase on POD-3 (r=0.45, p=0.04 and =-0.55, p=0.02, respectively). No significant correlations between F1+2 concentrations and platelet count changes have been found., Conclusions: Platelet reduction shortly after TAVI procedure is related to the amount of contrast agent applied during the procedure. Platelet activation and blood coagulation along with impaired baseline platelet renewal might be the mechanisms of thrombocytopenia following TAVI procedure., (Copyright © 2017 Elsevier Ltd. All rights reserved.)