Loose Fibrin Clot Structure and Increased Susceptibility to Lysis Characterize Patients with Central Acute Pulmonary Embolism: The Impact of Isolated Embolism

Discrimination of the acute pulmonary embolism subtypes based on the novel MAPH score

Acute pulmonary embolism (APE) is a thromboembolism situation that can be central or peripheral. APE risk analysis and classification are essential for therapy planning. Our aim is to determine the novel MAPH score (including age, mean platelet volume (MPV), total protein, and hematocrit parameters) that can distinguish APE subtypes. Our retrospective cohort analysis includes 97 APE patients referred to the emergency medicine department who underwent pulmonary computed tomography angiography (CTA) in 24 h from 2020 to 2022. The hospital information system provided demographic, clinical, laboratory, and pulmonary CTA data. APE was classified into central (46 patients) and peripheral (51 patients) depending on the area of vascular involvement. The central APE group had higher hypertension (HT) (67.4%) and atrial fibrillation (AF) (39.1%) incidence than the peripheral APE group (all p values > 0.05). The central APE had higher total protein and platelet counts (p = 0.003 and p = 0.036), but peripheral APE had higher troponin values (p = 0.029). Central APE had 2.17 ± 0.85 MAPH and peripheral APE 1.76 ± 0.95 (p = 0.029). HT, AF, platelet count, and MAPH score differed significantly in univariate logistic regression (all p values < 0.05). However, only platelet count varied in multivariate logistic regression (p = 0.042). ROC curve analysis revealed that the MAPH score predicts central APE with 83% sensitivity and 45% specificity at a cut-off level of 1.5. The new MAPH score as an indicator of blood viscosity may distinguish between central and peripheral APE. Our result is significant, especially for centers with limited examinations, as it may accelerate the diagnosis and treatment processes. We think that our results might guide future investigations.

Protocol for the Investigation of Plasma and Whole Blood Clot Property of Fibrin Fiber Thickness Using Scanning Electron Microscopy

Blood clot formation represents a key component of the coagulation process for preventing excessive hemorrhage. The structural characteristics of blood clots are associated with their strength and susceptibility to fibrinolysis. Scanning electron microscopy is a technique that allows for state-of-the-art image capture of blood clots, providing visualization of topography, fibrin thickness, fibrin network density, and blood cell involvement and morphology. In this chapter, we provide a detailed protocol for characterization of plasma and whole blood clot structure using SEM, covering the spectrum from blood collection, in vitro clot formation, sample preparation for SEM, imaging, and image analysis, specifically focusing on the measurement of fibrin fiber thickness.

Intermediate risk pulmonary embolism concomitant with or without lung cancer: a wide spectrum of features

OBJECTIVES

We aimed to investigate the differences in clinical features between pulmonary embolism (PE) patients concomitant with lung cancer and without lung cancer (LC) and gain further understanding of the impact of lung cancer on pulmonary embolism.

METHODS

This retrospective study sampled 114 patients diagnosed with pulmonary embolism from January 2017 to April 2021 in the First Affiliated Hospital of Soochow University. The patients were categorized into the LC group (n = 22) or non-LC group (n = 92). Myocardial injury, coagulation and blood cell parameters, along with imaging findings, were analyzed for the two groups. The primary outcome measure was the 90-day mortality.

RESULTS

Of the 114 patients with pulmonary embolism in the present study, the 90 intermediate-risk patients were enrolled for further investigations. Compared to the non-LC group, patients in the LC group had milder myocardial injury, more severe coagulation function disorder, a higher incidence of central PE and a smaller change in diameter of the main pulmonary artery. We found that the occurrence of pericardial effusion created the risk of lung cancer in patients with pulmonary embolism, but there was no increase in the 90-day mortality for non-LC group versus LC group.

CONCLUSION

Intermediate risk PE patients concomitant with lung cancer seem to be more likely to present specific clinical features, accordingly, clinicians must pay great attention to PE patients concomitant with lung cancer and implement effective treatments to simultaneously manage the two conditions.

Associations between coagulation factor XII, coagulation factor XI, and stability of venous thromboembolism: A case-control study

BACKGROUND

Pulmonary embolism (PE) is a fatal clinical syndrome that is generally caused by an embolus from unstable deep venous thrombosis (DVT). However, clinical and biochemical factors that are related to the stability of DVT are not fully understood.

AIM

To evaluate the relationships between plasma antigen levels of factor XII (FXII:Ag) and factor XI (FXI:Ag) with the stability of DVT.

METHODS

Patients with DVT and no PE, DVT and PE, and controls with no DVT or PE that matched for age, gender, and comorbidities were included in this study. FXII:Ag and FXI:Ag in peripheral venous blood were measured using enzyme-linked immunosorbent assays.

RESULTS

Using the 95^th percentile of FXI:Ag in patients with DVT and PE as the cut-off, a higher FXI:Ag was associated with a higher risk of unstable DVT (odds ratio: 3.15, 95% confidence interval: 1.18-8.43, P = 0.019). Stratified analyses showed consistent results in patients ≤ 60 years (P = 0.020), but not in those > 60 years (P = 0.346).

CONCLUSION

Higher plasma FXI:Ag might be a marker for unstable DVT, which might be associated with PE in these patients.

Associations between coagulation factor XII, coagulation factor XI, and stability of venous thromboembolism: A case-control study

BACKGROUND

Pulmonary embolism (PE) is a fatal clinical syndrome that is generally caused by an embolus from unstable deep venous thrombosis (DVT). However, clinical and biochemical factors that are related to the stability of DVT are not fully understood.

AIM

To evaluate the relationships between plasma antigen levels of factor XII (FXII:Ag) and factor XI (FXI:Ag) with the stability of DVT.

METHODS

Patients with DVT and no PE, DVT and PE, and controls with no DVT or PE that matched for age, gender, and comorbidities were included in this study. FXII:Ag and FXI:Ag in peripheral venous blood were measured using enzyme-linked immunosorbent assays.

RESULTS

Using the 95^th percentile of FXI:Ag in patients with DVT and PE as the cut-off, a higher FXI:Ag was associated with a higher risk of unstable DVT (odds ratio: 3.15, 95% confidence interval: 1.18-8.43, P = 0.019). Stratified analyses showed consistent results in patients ≤ 60 years (P = 0.020), but not in those > 60 years (P = 0.346).

CONCLUSION

Higher plasma FXI:Ag might be a marker for unstable DVT, which might be associated with PE in these patients.

Factor XIII and Fibrin Clot Properties in Acute Venous Thromboembolism

Coagulation factor XIII (FXIII) is converted by thrombin into its active form, FXIIIa, which crosslinks fibrin fibers, rendering clots more stable and resistant to degradation. FXIII affects fibrin clot structure and function leading to a more prothrombotic phenotype with denser networks, characterizing patients at risk of venous thromboembolism (VTE). Mechanisms regulating FXIII activation and its impact on fibrin structure in patients with acute VTE encompassing pulmonary embolism (PE) or deep vein thrombosis (DVT) are poorly elucidated. Reduced circulating FXIII levels in acute PE were reported over 20 years ago. Similar observations indicating decreased FXIII plasma activity and antigen levels have been made in acute PE and DVT with their subsequent increase after several weeks since the index event. Plasma fibrin clot proteome analysis confirms that clot-bound FXIII amounts associated with plasma FXIII activity are decreased in acute VTE. Reduced FXIII activity has been associated with impaired clot permeability and hypofibrinolysis in acute PE. The current review presents available studies on the role of FXIII in the modulation of fibrin clot properties during acute PE or DVT and following these events. Better understanding of FXIII’s involvement in the pathophysiology of acute VTE might help to improve current therapeutic strategies in patients with acute VTE.