Sporns PB, et al. - This study was performed to examine the effect of histologic thrombus features on the interventional outcome and procedure-related embolisms. Furthermore, the researchers aimed to evaluate the pre-interventional CT attenuation of the thrombi for a pre-interventional estimation of histologic features and outcome parameters. They found a significant association between fibrin-rich thrombi with low erythrocyte percentage and longer intervention times. In the thrombectomy process, embolisms occurred more often in thrombi with a small fraction of red blood cells and a low CT-density, implying a higher fragility of these thrombi.

• From December 2013 and February 2016, the researchers prospectively included all consecutive patients with occlusion of the middle cerebral artery who underwent thrombectomy at their university medical center.
• They histologically analyzed samples (H&E, Elastica van Gieson, Prussian blue), and performed immunohistochemistry for CD3, CD20, and CD68/KiM1P.
• They determined main thrombus components (fibrin, erythrocytes, and white blood cells) and compared to intervention time, the frequency of secondary embolisms, as well as additional clinical and interventional parameters.
• Furthermore, they evaluated the pre-interventional CT attenuation of the thrombi in relation to the unaffected side (rHU) and their association with histologic features.

• The researchers included 180 patients.
• Out of them, complete recanalization was achieved in 168 patients (93.4%), and 27 patients (15%) demonstrated secondary embolism in the control angiogram.
• A significant association of high amounts of fibrin (p < 0.001), low percentage of red blood cells (p < 0.001), and lower rHU (p < 0.001) with secondary embolism was observed.
• Higher rHU values were significantly correlated with higher amounts of fibrin (p ≤ 0.001) and low percentage of red blood cells (p ≤ 0.001).
• High amounts of fibrin were also correlated with longer intervention times (p ≤ 0.001), while thrombi with high amounts of erythrocytes correlated with shorter intervention times (p ≤ 0.001).
• In ROC analysis, they showed reliable prediction of secondary embolisms for low rHU (AUC = 0.746; p ≤ 0.0001), low amounts of RBC (AUC = 0.764; p ≤ 0.0001), and high amounts of fibrin (AUC = 0.773; p ≤ 0.0001).