Histopathologic analysis of extracted thrombi from deep venous thrombosis and pulmonary embolism: Mechanisms and timing

• Published in: Catheterization and cardiovascular interventions Vol. 97; no. 7; pp. 1422 - 1429
• Main Authors: Silver, Mitchell J., Kawakami, Rika, Jolly, Michael A., Huff, Christopher M., Phillips, John A., Sakamoto, Atsushi, Kawai, Kenji, Kutys, Bob, Guo, Liang, Cornelissen, Anne, Mori, Masayuki, Sato, Yu, Romero, Maria, Virmani, Renu, Finn, Aloke V.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-06-2021; Wiley Subscription Services, Inc
• Subjects: Blood clots; Catheters; deep vein thrombosis; Embolism; Endothelial cells; Erythrocytes; Fibrin; Inflammation; pathology; Patients; Proteoglycans; pulmonary artery embolism; Pulmonary embolisms; Smooth muscle; thrombectomy; Thrombosis; venous thromboembolism; pulmonary artery embolism; deep vein thrombosis; pathology; thrombectomy; venous thromboembolism
• ISSN: 1522-1946; 1522-726X
• DOI: 10.1002/ccd.29500

Background
Mechanical thrombectomy is increasingly being used as an alternative to pharmacologic therapies for the treatment of patients with acute deep venous thrombosis (DVT) and pulmonary embolism (PE) and allows direct histopathologic comparison of thrombi extracted from living patients. We performed histopathologic analysis to thrombi extracted from cases of DVT and PE to gain insights into their relative cellular compositions.
Methods
Thrombus retrieved using a catheter‐based thrombectomy system (ClotTriever for lower extremity DVT and FlowTriever for PE) from the 17 patients (7 DVT cases and 10 PE cases) were histologically evaluated. Histological features were used to estimate their age and pathological characteristics.
Results
The thrombus in all cases were composed of fibrin, platelets, red blood cells, and acute inflammatory cells. The weights of thrombus obtained from DVT versus PE cases were heavier (DVT 7.2 g (g) (5.6–10.2) vs. PE 4.8 g (3.6–6.8), p = .01). Overall thrombus healing (i.e., thrombus composed of smooth muscle cells, endothelial cells, and proteoglycans) was different between DVT and PE cases. 6/7 (86%) with features of late stage healing were from DVT cases while only three of ten (30%) were from PE cases while PE contained more acute thrombi with 7/10 (70%) stage 2 as compared 1/7 (14%) for DVT (p = .0498).
Conclusion
This study is the first to directly compare the histology of extracted thrombus in DVT versus PE cases from patients with clinical events. Overall PE cases demonstrated significantly earlier stage thrombus with a larger component of red blood cells.