Platelet function in patients undergoing major non-cardiac vascular surgery (PLUGS): a prospective cohort study.

INTRODUCTION: Patients who require major vascular surgery often receive antiplatelet therapy for primary or secondary prevention of cardiovascular disease. Clopidogrel resistance and variability in platelet recovery after drug discontinuation pose clinical challenges, particularly for regional anaesthesia and blood management. The aim of this study was to characterise platelet function and determine the prevalence of antiplatelet resistance using near-patient viscoelastic testing in patients undergoing major, elective non-cardiac vascular surgery. METHODS: We conducted a single-centre, prospective, observational cohort study at a tertiary vascular surgery centre. Adults scheduled for elective vascular surgery were recruited into four groups: aspirin; clopidogrel; dual antiplatelet therapy; and control (no antiplatelet therapy). Blood samples were obtained at pre-operative assessment and on the day of surgery. Platelet function was assessed using thromboelastography and von Willebrand factor antigen levels. The primary outcome was the proportion of patients with antiplatelet resistance. RESULTS: Eighty patients were enrolled, of whom 64 proceeded to surgery. Antiplatelet resistance was common, affecting 25-70% of patients at baseline depending on regimen and 15-83% on the day of surgery. Clopidogrel resistance was most frequent (70%). Two patients experienced early graft or stent thrombosis, both with evidence of clopidogrel resistance and elevated von Willebrand factor; von Willebrand factor levels exceeded the normal range in two-thirds of patients. In an exploratory analysis, clopidogrel cessation 5-7 days pre-operatively did not result in a statistically significant change in platelet inhibition. DISCUSSION: High rates of clopidogrel resistance and elevated von Willebrand factor were observed in patients with planned vascular surgery, suggesting that current peri-operative discontinuation guidelines may not restore normal platelet function. Larger multicentre studies that incorporate standardised platelet and near-patient genetic testing are required to validate these findings and guide personalised peri-operative antiplatelet management.