Red and White Thrombus Characteristics in Patients Undergoing Carotid Endarterectomy Hatice Tosun, MD,* Suat Kamı ¸ slı,† Mehmet Tecellio glu,† Saadet Alan,† Fahriye Se¸ cil Tecellio glu, MD,‡ Mustafa Namık € Oztanır,§ and Y€ uksel Kablan,† Objective: The study aimed to compare the characteristics of red and white thrombi in patients undergoing carotid endarterectomy. Material and Methods: The study was conducted in 81 patients with ischemic stroke who underwent carotid endar- terectomy for carotid artery stenosis. Carotid plaques were graded by two patholo- gists. Thrombus materials were divided into two groups: white and red. The parameters of assessment were plaque rupture, lipid core, fibrous cap thickness, inflammation, intraplaque hemorrhage, calcification, necrotic core, and neovascula- rization. Normally distributed data were evaluated using MannÀWhitney U and Chi-squared tests. Results: The ratio of white and red thrombus was 19.8% and 80.2%, respectively. Lipid core, plaque rupture, necrotic core, neovascularization, intraplaque hemorrhage, obstruction, and inflammation were observed more in red thrombus, which were statistically significant. Calcification and fibrous cap thick- ness were not statistically significant in the two groups. Moreover, intimal smooth muscle cells were present in all thrombus types. Conclusion: In our study, we found that red thrombi had more unstable characteristics than white thrombi. Thus, the risk for ischemic cerebrovascular events is more in red thrombi. However, this find- ing cannot be generalized due to the small number of patients in this study. There- fore, studies involving more patients are needed. Key Words: Fibrous cap thickness—Carotid plaque—Plaque rupture—Lipid core © 2020 Elsevier Inc. All rights reserved. Introduction Ischemic heart disease and stroke, which are associated with atherosclerosis in the coronary and carotid arteries, accounted for one-third of deaths worldwide. 1 The stroke type can be ischemic or hemorrhagic. Hemorrhagic stroke is divided into intracerebral and subarachnoid hemorrhage types. Ischemic stroke occurs because of small vessel occlu- sion, large artery atherosclerosis, cardiogenic embolism, and other causes. 2 Ischemic stroke and transient ischemic attack (TIA) usually arise from unstable carotid lesions, which cause thrombus formation or carotid artery occlusion. 3 Chronic or recurrent endothelial injury is a major factor in the pathogenesis of atherosclerosis. 4 Endothelial cell damage, along with other factors affecting the process (specific endothelial toxins, anoxia, carbon monoxide, or other cigarette smoke products), causes the development of structural disorders called atheroma or plaque. 4 Endo- thelial cell injury facilitates low-density lipoprotein and monocytes to pass the subendothelial area. 5 Early lesions of atherosclerosis occur when low-density lipoprotein is oxidized, the monocytes turn into macrophages to phago- cyte, and eventually, foam cells filled with fat particles are formed. Afterward, several inflammatory events are trig- gered, and advanced stages are formed. 5 Unstable plaque characteristics associated with the devel- opment of stroke are ruptured or thin fibrous cap, large lipid-rich necrotic core, intraplaque hemorrhage, inflamma- tion, intimal smooth muscle cells, thrombus, neovasculari- zation, and calcification. 3,6À8 The histological features of plaques can guide future studies, such as the study by. 9 The macroscopic view of the thrombus can also provide infor- mation regarding the present condition (Fig. 1). Thrombi From the *Fethi Sekin City Hospital, Elazı g, Turkey; †Turgut € Ozal Medical Center, Malatya, Turkey; ‡Malatya Training and Research Hospital, Malatya, Turkey; §Bezmialem University Medical Faculty, _ Istanbul, Turkey. Received May 14, 2020; revision received October 12, 2020; accepted October 31, 2020. Corresponding author. E-mail: drhaticetosun@gmail.com. 1052-3057/$ - see front matter © 2020 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jstrokecerebrovasdis.2020.105451 Journal of Stroke and Cerebrovascular Diseases, Vol. 30, No. 2 (February), 2021: 105451 1