Platelet Reactivity in PAD Undergoing Percutaneous Angioplasty

This is a single-center observational cohort study. All together 450 patients undergoing and elective PTA (both with and without stenting) who are going to be refereed to the Clinic for Vascular and Endovascular Surgery (based on the previous experience) during the two year period (January 1st 2020 and January 1st 2022) are planned to be involved in this study. All interventions will be performed according to the current standards and the type of the endovascular procedure will be at the discretion of operator. All patients will receive at the day of treatment 300mg of Aspirin and 300mg of Clopidogrel. The day after the procedure platelet function will be assessed by "point-of-care" impedance aggregometry test using the Multiplate analyzer. According to the manufacturer proposition, resistancy on Aspirin will be defined as arachidonic acid receptor (ASPI) value < 600 and ASPI/thrombin receptor activating peptide (TRAP) < 0.5, and for Clopidogrel adenosine diphosphate (ADP) < 500 and ADP/TRAP < 0.5 . After that patients will receive dual antiplatelet therapy (Aspirin 100mg and Clopidogrel 75mg) in the six months period. Follow-up examinations will be scheduled on 1, 6 and 12 months after the intervention. Adherence to antiplatelet treatment will assessed during scheduled or unscheduled examinations. Statistical analysis will be performed using the software package SPSS 20 (SPSS Inc., Chicago, Il, USA). Categorical data will be represented as numbers and percentages. Chi-square test or Fisher exact test as appropriate will be used to compare categorical data. Continuous variables will be represented as mean ± standard deviation and as median and interquartile range, depending on the normality of data. Student's t test or Mann-Whitney U test as appropriate will be used to compare two population groups. We will then assess the ability of ASPI and ADP values to distinguish between patients with and without clinical event at 6 months follow up by receiver-operating characteristic (ROC) curve analysis and the optimal cut-off ASPI and ADP values will be determined by estimating the value resulting in the maximum sum of sensitivity and specificity (area under the curve - AUC). Kaplan-Meier curves with log-rank test will be used to assess difference in the time-to-event end-points. A multivariable Cox proportional hazard model adjusted for clinical and laboratory variables will be performed to evaluate the independent contribution of platelet hyper- or hypo-reactivity to the outcomes. A P-values <0.05 will be considered statistically significant.