Background: Stent thrombosis is a rare but deleterious event. Routine coronary angiography with percutaneous coronary intervention (PCI) is often deferred in the presence of laboratory markers of acute inflammation to prevent complications. The aim of this study was to investigate whether an acute inflammatory state is associated with an increased risk of early stent thrombosis. Methods and Results: Within a prospective single‐center registry, the association between preprocedural acute inflammatory activation, defined as C‐reactive protein plasma levels >50 mg/L or a leukocyte count >12 g/L, and occurrence of early (≤30 days) stent thrombosis was evaluated. In total, 11 327 patients underwent PCI and of those, 6880 patients had laboratory results available. 49.6% of the study population received PCI for an acute coronary syndrome and 50.4% for stable ischemic heart disease. In patients with signs of acute inflammatory activation (24.9%), PCI was associated with a significantly increased risk for stent thrombosis (hazard ratio, 2.89; P <0.00001), independent of age, sex, kidney function, number and type of stents, presence of multivessel disease, choice of P2Y12 inhibitor, and clinical presentation. Elevated laboratory markers of acute inflammation were associated with the occurrence of stent thrombosis in both patients with acute coronary syndrome (hazard ratio, 2.63; P <0.001) and in patients with stable ischemic heart disease (hazard ratio, 3.57; P <0.001). Conclusions: An acute inflammatory state at the time of PCI was associated with a significantly increased risk of early stent thrombosis. Evidence of acute inflammation should result in deferred PCI in elective patients, while future studies are needed for patients with acute coronary syndrome.

Background/Objectives: Acute stent thrombosis (ST) is a rare yet severe complication following percutaneous coronary intervention (PCI). Herein, we investigated the possible association between routinely available coagulation and fibrinolysis markers with early ST. Methods: Within a single-center registry, we investigated the association between the preprocedural platelet count, plasma levels of fibrinogen and D-Dimer, and the incidence of early ST in the first 30 days after PCI. Results: Out of 10,714 consecutive patients who underwent PCI using drug-eluting stents (DESs), the preprocedural platelet count, fibrinogen, and D-Dimer measurements were available in 6337, 6155, and 956 patients, respectively. Fifty-eight patients (0.92%) experienced an early ST within 30 days after PCI. Compared with those without ST, patients with early ST showed significantly elevated preprocedural platelet counts (p < 0.05) and fibrinogen levels (p < 0.05). D-Dimer levels were not associated with early ST. Patients in the fifth quintile of platelet count had a significantly increased risk for early ST (HR 2.43; 95% CI 1.43–4.14; p = 0.001) compared with patients in the lower four quintiles. In addition, patients in the fifth quintile of fibrinogen also had a significantly increased risk for early ST (HR 1.86; 95% CI 1.07–3.26; p < 0.05) compared with patients in the lower four quintiles. These associations were independent of clinical risk factors, the number of stents, the presence of acute coronary syndromes, and white blood cell count. Conclusions: Preprocedural platelet counts and fibrinogen plasma levels can identify patients at elevated risk of early ST after implantation of DESs in addition to procedure-level and device-related risk factors.