BackgroundPeriprocedural bleeding events are common after percutaneous coronary intervention. We evaluated the association of periprocedural bleeding events with thrombogenicity, which was measured quantitatively by the Total Thrombus‐formation Analysis System equipped with microchips and thrombogenic surfaces (collagen, platelet chip [PL]; collagen plus tissue factor, atheroma chip [AR]).Methods and ResultsBetween August 2013 and March 2016, 313 consecutive patients with coronary artery disease undergoing elective percutaneous coronary intervention were enrolled. They were divided into those with or without periprocedural bleeding events. We determined the bleeding events as composites of major bleeding events defined by the International Society on Thrombosis and Hemostasis and minor bleeding events (eg, minor hematoma, arteriovenous shunt and pseudoaneurysm). Blood samples obtained at percutaneous coronary intervention were analyzed for thrombus formation area under the curve (PL24‐AUC10 for PL chip; AR10‐AUC30 for AR chip) by the Total Thrombus‐formation Analysis System and P2Y12 reaction unit by the VerifyNow system. Periprocedural bleeding events occurred in 37 patients. PL24‐AUC10 levels were significantly lower in patients with such events than those without (P=0.002). Multiple logistic regression analyses showed association between low PL24‐AUC10 levels and periprocedural bleeding events (odds ratio, 2.71 [1.22–5.99]; P=0.01) and association between PL24‐AUC10 and periprocedural bleeding events in 176 patients of the femoral approach group (odds ratio, 2.88 [1.11–7.49]; P=0.03). However, PL24‐AUC10 levels in 127 patients of the radial approach group were not significantly different in patients with or without periprocedural bleeding events.ConclusionsPL24‐AUC10 measured by the Total Thrombus‐formation Analysis System is a potentially useful predictor of periprocedural bleeding events in coronary artery disease patients undergoing elective percutaneous coronary intervention.