Morphologic change in deep venous thrombosis in the lower extremity after therapeutic anticoagulation

BACKGROUND: To evaluate the anticoagulant treatment response in venous thrombi with different morphologies (size, shape, and echogenicity) by measuring the change in thrombus thickness. MATERIALS AND METHODS: This was a retrospective cohort study of 97 lower extremity DVT patients diagnosed by venous ultrasound between March 2014 and February 2018. The demographics, clinical risk factors, anticoagulant treatment, and ultrasound findings at the first diagnosis and 2-6 months after treatment were evaluated. RESULTS: The anticoagulant treatment with LMWH followed by VKAs showed a significant decrease in the mean maximum difference in lower extremity DVT thrombus thickness compared with VKAs alone (P-value < 0.001). After adjustment by treatment, the thrombi found in dilated veins showed a significant decrease in the thickness of such thrombi compared with those found in small veins: 4 mm vs. 0 mm (Coef. = 3, 95% CI: 1.9, 4.1 and P-value < 0.001). Anechoic and hypoechoic thrombi showed a significant decrease in the thickness compared with hyperechoic thrombi: 5 mm vs. 0 mm (Coef. = 4, 95% CI: 3.25, 4.74 and P-value < 0.001) and 3 mm vs. 0 mm (Coef. = 2, 95% CI: 1.34, 42.66 and P-value < 0.001), respectively. Concentric thrombi showed a significant decrease in thickness compared with eccentric thrombi: 4 mm vs. 0 mm (Coef. = 2, 95% CI: 1.45, 2.55 and P-value < 0.001). CONCLUSION: The anticoagulant treatment with LMWH followed by VKAs shows a significant decrease in lower extremity DVT thrombus thickness compared with VKAs alone. After adjustment by treatment, the morphologic finding of acute thrombi shows a significantly decreased thickness compared with the morphologic finding of chronic thrombi.