Fibrin-Platelet Clots in Acute Ischemic Stroke. Predictors and Clinical Significance in a Mechanical Thrombectomy Series

 You'll need to be awake enough when your doctor tells you you have a fibrin-predominant clot (FPC) and you get better recalization but have higher mortality using a stent retriever. Then ask for better options.

Fibrin-Platelet Clots in Acute Ischemic Stroke. Predictors and Clinical Significance in a Mechanical Thrombectomy Series

Francisco Hernández-Fernández^1†, María E. Ramos-Araque^2,3*†, Rosa Barbella-Aponte⁴, Juan David Molina-Nuevo⁵, Jorge García-García¹, Oscar Ayo-Martin¹, María José Pedrosa-Jiménez⁵, Lorena López-Martinez⁵, Gemma Serrano-Heras⁶, Enrique Julia-Molla⁵ and Tomás Segura^1,7

• ¹Department of Neurology, Hospital General Universitario de Albacete, Albacete, Spain
• ²Department of Neurology, University Hospital of Salamanca, Biomedical Research Institute of Salamanca, Salamanca, Spain
• ³Department of Neurology, University Hospital of Valladolid, Valladolid, Spain
• ⁴Department of Surgical Pathology, Hospital General Universitario de Albacete, Albacete, Spain
• ⁵Department of Radiology, Hospital General Universitario de Albacete, Albacete, Spain
• ⁶Research Unit, Hospital General Universitario de Albacete, Albacete, Spain
• ⁷Instituto de Investigación en Discapacidades Neurológicas (IDINE), Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain

Introduction: The histological composition of the clot influences its mechanical properties, affects the efficacy of endovascular treatment (EVT), and could determine the clinical outcome of patients with acute ischemic stroke (AIS). Insights into clot composition may guide therapeutic decision-making prior to EVT and facilitate revascularization therapies.

Material and Methods: Consecutive patients with AIS recorded in a prospective single-center reperfusion registry from December 2015 to December 2019 and treated with EVT were included. Baseline, laboratory [including post-procedural C-reactive protein (CRP)], radiological, and angiographic variables were analyzed. We aimed to study the relationship between histological composition of the clot with basal neuroimaging, laboratory markers, and recanalization technique. The secondary outcome was to analyze the correlation between clot composition and functional outcome at 3 months assessed by the modified Rankin scale (mRS).

Results: From the study period, 360 AIS patients treated with EVT were included, of whom 189 (53%) fulfilled the inclusion criteria. One hundred (53%) cases of fibrin-predominant clot (FPC) were recorded. Full recanalization in FPC cases was achieved with higher probability when stent retrievers (SR) were selected as the first-line device (68.2%, p = 0.039). Patients with FPC had higher levels of CRP (p = 0.02), lower frequency of the hyperdense middle cerebral artery (HMCA) in baseline imaging (p = 0.039), and higher rates of mortality (p = 0.012). The multivariate analysis showed that the absence of HMCA (OR = 0.420; 95% CI 0.197–0.898; p = 0.025) and higher levels of CRP (OR = 1.01; 95% CI 1.003–1.019; p = 0.008) were predictors of FPC. Leukocytes and platelet counts were not associated with clot histology.

Conclusions: The absence of HMCA and higher levels of CRP were markers of FPC. In patients with FPC, complete recanalization was most likely to be achieved when a SR was selected as first line of treatment. Mortality was higher in patients within this histologic group.

Introduction

Endovascular treatment (EVT) has become the standard of care in patients with acute ischemic stroke (AIS) and large-vessel occlusion (1). Complete recanalization and first-pass recanalization have been shown to be independent predictors of good functional outcome (2–4). However, these endpoints are currently achieved in <50% of patients, probably due to inadequate patient selection or factors related to the procedure (5).

One of the main reasons for the lack of efficacy of EVT is the scant knowledge of the mechanical properties of the clot (6–8) and its histological composition. Both factors are relevant to attainment of successful reperfusion (9) and could aid in the development of endovascular thrombectomy devices.

Based on the predominant cell type, clots are usually divided into red clots (RPC), white or fibrin-rich clots (FPC), and mixed clots (MC) (10). In addition, the distribution of the fibrin network (6) and platelet clumps can be highly variable (11). Therefore, some FPC are more resistant to revascularization than others due to their higher friction coefficient (7, 8, 12). On the other hand, RPC demonstrate a lower density and are more easily removed as a result. A better understanding of the histological composition of the clot could facilitate better clinical and angiographic outcomes.

We aimed to study the relationship between histological composition of the clot with basal neuroimaging, laboratory markers, and recanalization strategies including intravenous thrombolysis and clot retrieval devices. The secondary outcome was to analyze the correlation between clot composition and functional outcome at 3 months as assessed by the modified Rankin scale (mRS).

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