Body weight: a risk factor for subtherapeutic antithrombotic therapy in neurovascular stenting

Background Patients with cervical carotid and intracranial stenting are routinely premedicated with antithrombotic agents, clopidogrel and aspirin (ASA), and intraprocedurally with heparin. The levels of antithrombotic therapy necessary for these neurovascular therapies have yet to be well defined. Method A retrospective review of 52 patients who underwent neurovascular stenting procedures was carried out. Measurements obtained intraoperatively included: activating clotting time, antiplatelet inhibition (from Accumetrics) recorded as ASA reaction units (ARU), P2Y12 reaction units (PRU), baseline (BASE), and percentage inhibition. Percentage P2Y12 platelet inhibition <20% and ARU >550 were defined as suboptimal clopidogrel and ASA responses, respectively. Results 52 patients (mean age 62.6 years) underwent stent implantation for wide necked aneurysms (28, 54%), symptomatic intracranial stenosis (13, 25%) and cervical carotid stenosis (11, 21%). Mean ARU assays were 463.0+/-84.7. The response was suboptimal in seven patients. For clopidogrel, the mean BASE, PRU and percentage inhibition were 374.0+/-54.9, 279.5+/-78.5 and 30.7%+/-22.6%, respectively. 19 patients (36.5%; p<0.01) showed suboptimal responses for percentage inhibition. Multivariate analysis showed that body weight (82.0+/-11 vs 73.6+/-14 kg; p=0.04) and body mass index were significant predictors (OR 1.18, 95% CI 1.01 to 1.18; p=0.003) in the suboptimal group. One case of intraprocedural thrombosis (2%) was observed in the suboptimal group and no cases were seen in the therapeutic group. Conclusion Data obtained in this study suggest a suboptimal clopidogrel response in patients with greater body weight and body mass index. Adjusted dosing according to weight may help achieve adequate therapeutic platelet inhibition and reactivity while decreasing thromboembolic complications.