Acute Ischemic Stroke Thrombus Composition

Histological differences among thrombi in thrombotic diseases

PURPOSE OF REVIEW

This review aims to summarize the histological differences among thrombi in acute myocardial infarction, ischemic stroke, venous thromboembolism, and amniotic fluid embolism, a newly identified thrombosis.

RECENT FINDINGS

Acute coronary thrombi have a small size, are enriched in platelets and fibrin, and show the presence of fibrin and von Willebrand factor, but not collagen, at plaque rupture sites. Symptomatic deep vein thrombi are large and exhibit various phases of time-dependent histological changes. Cancer-associated venous thromboemboli contain invasive cancer cells that penetrate the vascular walls, and small cancer cell aggregates are observed within the thrombi. The thrombus composition in atherosclerotic and cardioembolic ischemic strokes varies from case to case, while the thrombi in cancer-associated ischemic stroke are rich in platelets and fibrin. A pathological study on amniotic fluid embolism identified uterine vein thrombi and massive platelet-rich microthrombi in the lungs.

SUMMARY

Atherothrombus formation is induced by plaque disruption and may occlude a narrow lumen within a short time. Venous thrombi may grow to a large size in a multistage or chronic manner. Cancer cells can directly contribute to venous thrombus formation. The thrombus formation in amniotic fluid embolism may explain the occurrence of consumptive coagulopathy and cardiopulmonary collapse.

Targeting the Ischemic Core: A Therapeutic Microdialytic Approach to Prevent Neuronal Death and Restore Functional Behaviors

Ischemic stroke leads to cerebral ionic imbalance, increases acidosis, oxidative stress and release of glutamate and inflammatory mediators. Removing solute or stimulants from the ischemic core may block cell-damaging events and confer neuroprotection. In this study, we developed a minimally invasive therapeutic microdialysis (tMD) method, choosing to include serum albumin in the buffer because it is a multifunctional protein with osmotic properties. Aiming at the ischemic core, continuous perfusion of buffer supplemented with osmotic agents removes mediators of inflammation/cell damage/death from the lesion. This tMD treatment significantly removed the glutamate and zinc ions from the core, thereby reducing infarct volumes and affording high-grade neurobehavioral protection against ischemic stroke. The tMD treatment effectively protected neurons and reduced microglial activation. Furthermore, this tMD approach extended the therapeutic window to protect beyond 6 h after stroke onset. These findings support the potential clinical feasibility of applying tMD to patients with ischemic stroke, potentially without adverse effects.

Procedural and Clinical Outcome of Stroke after thrombectomy according to etiology: results from a nationwide registry

BACKGROUND

The impact of stroke etiology on outcomes in patients who underwent endovascular thrombectomy (EVT) is still a matter of debate. We studied the effect of aterosclerotic versus cardioembolic etiology on the clinical and radiological outcome of patients with stroke due to large vessel occlusion (LVO) treated with EVT on a large sample of stroke patients enrolled in a nationwide registry.

METHODS

The source of data was the Italian Registry of Endovascular Stroke Treatments, a national, prospective, observational internet-based registry including patients treated with EVT since 2011. We extracted and compared data of patients suffering from large atherosclerosis (LAA) or cardioembolic (CE) stroke.

RESULTS

We included 5193 patients, 3899 CE, and 1294 LAA stroke. Patients with CE were significantly older (p < 0.001), and their stroke severity at admission was significantly higher (p < 0.001). Moreover, patients with LAA had significantly longer onset to end of procedure time, and procedure duration than CE patients. Good outcome at three months was reported in 45.2% of LAA and 45.4% of CE patients (p = 0.89). In the multivariable analysis, patients with CE had higher odds of achieving successful (OR = 1.61; 95% CI 1.35-1.92) or complete (OR = 1.40; 95% CI 1.21-1.62) recanalization Futile recanalization was detected more frequently in CE patients (OR = 1.35; 95% CI 1.18-1.61). There were no statistically significant differences in clinical outcomes (mRS 02: OR = 1.12; 95% CI 0.92-1.36). LAA patients had higher odds of sICH (OR = 0.65; 95% CI 0.49-0.85). The shift analysis showed a trend toward a better outcome in CE patients (OR = 1.19; 95% CI 0.99-1.35), which was statistically significant in subjects with anterior circulation stroke. (OR = 1.21; 95% CI 1.04-1.35).

CONCLUSIONS

The study showed a better chance of successful recanalization in CE patients, a slightly better outcome in CE patients with anterior circulation stroke after adjusting for baseline confounders, despite their more unfavourable risk factor profile, and a higher chance of futile recanalization.

Association Between Thrombus Composition and Etiology in Patients With Acute Ischemic Stroke Treated by Thrombectomy

BACKGROUND

In ischemic stroke due to large vessel occlusion, cerebral blood flow is impaired by thromboemboli, which can originate from various sources in the body. A better understanding of thromboembolus composition can improve our understanding of the underlying pathophysiology and potentially guide improvement of prevention strategies. The aim of this study therefore was to perform a large-sample multi-parameter quantitative histological analysis of retrieved thromboemboli from stroke patients.

METHODS

Thromboemboli (n=501) were collected from thrombectomy-treated ischemic stroke patients at AZ Groeninge Hospital (Kortrijk, Belgium) and CHU Lille (Lille, France). Stroke etiology was determined by the treating stroke specialist using the TOAST classification system (Trial of ORG 10172 in Acute Stroke Treatment). Extensive histological analysis, blinded to stroke etiology, was performed for key thrombus constituents including red blood cells (RBCs), platelets, fibrin, von Willebrand Factor, leukocytes, citrullinated histone H3 (as a marker for neutrophil extracellular traps), and extracellular (ex)DNA. Quantitative histology results were linked to etiology.

RESULTS

Compared with large-artery atherosclerotic thromboemboli, cardioembolic thromboemboli contained significantly fewer RBCs and significantly more platelets, fibrin, leukocytes, and exDNA. Interestingly, cryptogenic thromboemboli contained relatively low amounts of RBCs and high amounts of platelets, similar to cardioembolic thromboemboli. A multivariable logistic regression model indicated that it is difficult to predict stroke etiology based on the individual thrombus composition.

CONCLUSIONS

Based on a large sample cohort of stroke thromboemboli, we found that cardiac thromboemboli contained fewer RBCs and more platelets than atherosclerotic thromboemboli and that cryptogenic thromboemboli have a similar composition to cardiac thromboemboli in terms of RBCs and platelets.