Alterations in clot microstructure in acute exacerbations of COPD

Background: Chronic Obstructive Pulmonary Disease (COPD) patients are prone to thrombogenic events, particularly during exacerbations. Fractal dimension (df), a functional biomarker of clot microstructure is useful in assessing thrombogenicity in other diseases. The aim of this study was to compare the changes in df during acute exacerbation of COPD with stable disease. Methods: This prospective study recruited 30 patients with stable disease from the chest clinic and 85 patients with acute exacerbations from the Emergency Department. The stable group had blood samples taken at one time point, whilst the exacerbation group were sampled at four time points (0 hours, 4-6 hours, 24 hours and 3-7 days). Biomarkers of inflammation, haemostasis and rheology were determined. Results: At presentation, the acute exacerbation group had significantly elevated df when compared to the stable group (1.71 ± 0.06 vs 1.69 ± 0.05, p=0.03) but with no significant changes in df over the four time points (p=0.28) sampled. The patients who died in the acute exacerbation group had significantly elevated df when compared to those who survived (1.76 ± 0.03 vs 1.71 ± 0.06, p=0.02) with additional logistic regression analysis confirming that dfwas a significant predictor of mortality (p=0.024). Conclusions: Clot microstructural analysis demonstrates that COPD patients during acute exacerbation are more thrombogenic when compared to those with stable disease. This thrombogenic state is not aggravated with appropriate treatment on admission. Patients who died during exacerbations were in a significantly enhanced thrombogenic state when compared to those who survived as demonstrated by significantly elevated df.