Multiple electrode aggregometry predicts stent thrombosis better than the vasodilator-stimulated phosphoprotein phosphorylation assay.

Abstract

The prognostic value of the vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay and multiple electrode aggregometry (MEA) for thrombotic adverse events has been shown in independent studies. As no direct comparison between the two methods has been made so far, we investigated which laboratory approach has a better predictive value for stent thrombosis. The VASP phosphorylation assay and MEA were performed in 416 patients with coronary artery disease undergoing percutaneous coronary intervention. The rate of stent thrombosis was recorded during a 6-month follow-up. Definite stent thrombosis occurred in three patients (0.7%) and probable stent thrombosis in four (1%). Receiver operating characteristic (ROC) analysis demonstrated that MEA distinguishes between patients with or without subsequent stent thrombosis better than the VASP phosphorylation assay: the area under the ROC curve was higher for MEA (0.92; P=0.012) than for the VASP phosphorylation assay (0.60; P=0.55). At equal levels of sensitivity (100%), the specificity was greater for MEA than for the VASP phosphorylation assay (86% vs. 37%). Stent thrombosis occurred in 9% of patients with platelet hyperreactivity in MEA, who were simultaneously clopidogrel non-responders in the VASP phosphorylation assay. Interestingly, clopidogrel non-responders in the VASP phosphorylation assay without platelet hyperreactivity in MEA did not suffer from stent thrombosis. Platelet hyperreactivity in MEA might be a better risk predictor for stent thrombosis than the assessment of the specific clopidogrel effect with the VASP phosphorylation assay.