Background: Chronic obstructive pulmonary disease (COPD) is associated with a high risk of cardiovascular events, during acute exacerbations (AE) and for several weeks afterward. Extracellular vesicles (EV) increase in COPD, particularly during AE. A subset of EV expresses tissue factor (TF), the initiator of blood coagulation, and is therefore prothrombotic.

Aim: To compare TF-bearing EV (EV-TF) in stable and AECOPD patients.

Methods: 15 patients with AECOPD were enrolled within 48 hours of hospital access and reassessed 8 weeks later. 24 stable patients (no AECOPD in the previous year) were also enrolled; 6 of them were re-evaluated at 6 months. EV were isolated by differential centrifugation from 4 mL of blood. The final pellet (16,000xg for 45 min) was resuspended in 100 ?L saline and tested for TF with a one-stage clotting assay.

Results: EV-TF was significantly higher in exacerbators than in stable patients, both at AE and after 8 weeks. In the 6 stable patients that were tested twice, EV-TF did not vary over 6 months (figure).

Conclusions: EV-TF is higher in exacerbators than in stable patients and remains higher for at least 8 weeks. These data are consistent with the hypothesis that an increase in EV-TF is responsible for the increased risk of cardiovascular events in COPD exacerbators that extends for several weeks after AE.