Caging the dragon: Research approach to COVID-19-related thrombosis

Bilateral lower limb examinations for deep vein thrombosis: A single-centre pilot study comparing request and report parameters for bilateral and unilateral referrals

INTRODUCTION

Deep vein thrombosis (DVT) is a common pathology with significant morbidity and mortality, often occurring in the lower limb. Ultrasound is the modality of choice for diagnosis of DVT, but all guidance in the United Kingdom assumes a single leg referral. Few studies have addressed the question of bilateral referrals and bilateral DVTs, and it is not known how these should be included in ultrasound protocols. This study aims to compare the request and report parameters of bilateral examinations with those for single leg examinations over a six-month period.

METHODS

A single-centre feasibility study collected data on all single and bilateral leg examinations performed by sonographers, over a six-month period at a small general hospital. Data collected for each examination included the referral and report findings. These were compared using basic statistical methods to compare DVT yield by laterality, referrer, DVT site, and patient factors.

RESULTS

Six hundred and thirty examinations were included, eighteen of which were bilateral examinations. Although the bilateral leg cohort was small, there were significant differences in DVT yield between the groups, with single leg referrals more than eight times more likely to demonstrate a DVT at ultrasound.

CONCLUSION

In a context of limited ultrasound resource, the low DVT yield of bilateral examinations has implications for service design. Further data collection will be needed to validate initial results, and to establish suitable criteria for acceptance of bilateral DVT referrals.

IMPLICATIONS FOR PRACTICE

Low yield of DVTs in bilateral examinations can be validated via further research. Bilateral examinations can be explicitly included in DVT service design.

Post-Pulmonary Embolism Syndrome and Functional Outcomes after Acute Pulmonary Embolism

Survivors of acute pulmonary embolism (PE) are at risk of developing persistent, sometimes disabling symptoms of dyspnea and/or functional limitations despite adequate anticoagulant treatment, fulfilling the criteria of the post-PE syndrome (PPES). PPES includes chronic thromboembolic pulmonary hypertension (CTEPH), chronic thromboembolic pulmonary disease, post-PE cardiac impairment (characterized as persistent right ventricle impairment after PE), and post-PE functional impairment. To improve the overall health outcomes of patients with acute PE, adequate measures to diagnose PPES and strategies to prevent and treat PPES are essential. Patient-reported outcome measures are very helpful to identify patients with persistent symptoms and functional impairment. The primary concern is to identify and adequately treat patients with CTEPH as early as possible. After CTEPH is ruled out, additional diagnostic tests including cardiopulmonary exercise tests, echocardiography, and imaging of the pulmonary vasculature may be helpful to rule out non-PE-related comorbidities and confirm the ultimate diagnosis. Most PPES patients will show signs of physical deconditioning as main explanation for their clinical presentation. Therefore, cardiopulmonary rehabilitation provides a good potential treatment option for this patient category, which warrants testing in adequately designed and executed randomized trials. In this review, we describe the definition and characteristics of PPES and its diagnosis and management.

Levels of Fibrinogen Variants Are Altered in Severe COVID-19

Background  Fibrinogen variants as a result of alternative messenger RNA splicing or protein degradation can affect fibrin(ogen) functions. The levels of these variants might be altered during coronavirus disease 2019 (COVID-19), potentially affecting disease severity or the thrombosis risk. Aim  To investigate the levels of fibrinogen variants in plasma of patients with COVID-19. Methods  In this case-control study, we measured levels of functional fibrinogen using the Clauss assay. Enzyme-linked immunosorbent assays were used to measure antigen levels of total, intact (nondegraded Aα chain), extended Aα chain (α _E ), and γ' fibrinogen in healthy controls, patients with pneumococcal infection in the intensive care unit (ICU), ward patients with COVID-19, and ICU patients with COVID-19 (with and without thrombosis, two time points). Results  Healthy controls and ward patients with COVID-19 ( n  = 10) showed similar fibrinogen (variant) levels. ICU patients with COVID-19 who later did ( n  = 19) or did not develop thrombosis ( n  = 18) and ICU patients with pneumococcal infection ( n  = 6) had higher absolute levels of functional, total, intact, and α _E fibrinogen than healthy controls ( n  = 7). The relative α _E fibrinogen levels were higher in ICU patients with COVID-19 than in healthy controls, while relative γ' fibrinogen levels were lower. After diagnosis of thrombosis, only the functional fibrinogen levels were higher in ICU patients with COVID-19 and thrombosis than in those without, while no differences were observed in the other fibrinogen variants. Conclusion  Our results show that severe COVID-19 is associated with increased levels of α _E fibrinogen and decreased relative levels of γ' fibrinogen, which may be a cause or consequence of severe disease, but this is not associated with the development of thrombosis.

Risk of Thrombosis during and after a SARS-CoV-2 Infection: Pathogenesis, Diagnostic Approach, and Management

Coronavirus disease 2019 (COVID-19) increases the risk of thromboembolic events, especially in patients with severe infections requiring intensive care and cardiorespiratory support. COVID-19 patients with thromboembolic complications have a higher risk of death, and if they survive, these complications are expected to negatively affect these patients’ quality of life. Moreover, recent data reported that the risk of thromboembolism remains high months after a COVID-19 infection. Therefore, understanding the pathogenesis of thrombosis in the setting of COVID-19 may facilitate the early prevention and treatment of COVID-19-associated thromboembolism to reduce concomitant morbidity, mortality, and disability. This review will first discuss the clinical characteristics of COVID-19 infections, particularly with regard to the underlying pathophysiology. Then, the pathogenesis of COVID-19-associated thrombosis at the molecular and cellular levels will be comprehensively reviewed. Next, the clinical manifestations of venous and arterial thromboembolism in COVID-19 as well as the potential benefits of several laboratory markers of thrombosis will be further discussed. Lastly, the preventive and therapeutic management of thromboembolism during and after COVID-19 will also be explained.

Prevalence, pathophysiology, prediction and health-related quality of life of long COVID: study protocol of the longitudinal multiple cohort CORona Follow Up (CORFU) study

INTRODUCTION

The variety, time patterns and long-term prognosis of persistent COVID-19 symptoms (long COVID-19) in patients who suffered from mild to severe acute COVID-19 are incompletely understood. Cohort studies will be combined to describe the prevalence of long COVID-19 symptoms, and to explore the pathophysiological mechanisms and impact on health-related quality of life. A prediction model for long COVID-19 will be developed and internally validated to guide care in future patients.

METHODS AND ANALYSIS

Data from seven COVID-19 cohorts will be aggregated in the longitudinal multiple cohort CORona Follow Up (CORFU) study. CORFU includes Dutch patients who suffered from COVID-19 at home, were hospitalised without or with intensive care unit treatment, needed inpatient or outpatient rehabilitation and controls who did not suffer from COVID-19. Individual cohort study designs were aligned and follow-up has been synchronised. Cohort participants will be followed up for a maximum of 24 months after acute infection. Next to the clinical characteristics measured in individual cohorts, the CORFU questionnaire on long COVID-19 outcomes and determinants will be administered digitally at 3, 6, 12, 18 and 24 months after the infection. The primary outcome is the prevalence of long COVID-19 symptoms up to 2 years after acute infection. Secondary outcomes are health-related quality of life (eg, EQ-5D), physical functioning, and the prevalence of thromboembolic complications, respiratory complications, cardiovascular diseases and endothelial dysfunction. A prediction model and a patient platform prototype will be developed.

ETHICS AND DISSEMINATION

Approval was obtained from the medical research ethics committee of Maastricht University Medical Center+ and Maastricht University (METC 2021-2990) and local committees of the participating cohorts. The project is supported by ZonMW and EuroQol Research Foundation. Results will be published in open access peer-reviewed scientific journals and presented at (inter)national conferences.

TRIAL REGISTRATION NUMBER

NCT05240742.

Lupus anticoagulant associates with thrombosis in patients with COVID-19 admitted to intensive care units: A retrospective cohort study

Background

Thrombosis is a frequent and severe complication in patients with coronavirus disease 2019 (COVID‐19) admitted to the intensive care unit (ICU). Lupus anticoagulant (LA) is a strong acquired risk factor for thrombosis in various diseases and is frequently observed in patients with COVID‐19. Whether LA is associated with thrombosis in patients with severe COVID‐19 is currently unclear.

Objective

To investigate if LA is associated with thrombosis in critically ill patients with COVID‐19.

Patients/Methods

The presence of LA and other antiphospholipid antibodies was assessed in patients with COVID‐19 admitted to the ICU. LA was determined with dilute Russell's viper venom time (dRVVT) and LA‐sensitive activated partial thromboplastin time (aPTT) reagents.

Results

Of 169 patients with COVID‐19, 116 (69%) tested positive for at least one antiphospholipid antibody upon admission to the ICU. Forty (24%) patients tested positive for LA; of whom 29 (17%) tested positive with a dRVVT, 19 (11%) tested positive with an LA‐sensitive aPTT, and 8 (5%) tested positive on both tests. Fifty‐eight (34%) patients developed thrombosis after ICU admission. The odds ratio (OR) for thrombosis in patients with LA based on a dRVVT was 2.5 (95% confidence interval [CI], 1.1–5.7), which increased to 4.5 (95% CI, 1.4–14.3) in patients at or below the median age in this study (64 years). LA positivity based on a dRVVT or LA‐sensitive aPTT was only associated with thrombosis in patients aged less than 65 years (OR, 3.8; 95% CI, 1.3–11.4) and disappeared after adjustment for C‐reactive protein.

Conclusion

Lupus anticoagulant on admission is strongly associated with thrombosis in critically ill patients with COVID‐19, especially in patients aged less than 65 years.

Pulmonary thromboembolic events in COVID‐19 – a systematic literature review

Pulmonary thromboembolic events have been linked to coronavirus disease 2019 (COVID‐19), but their incidence and long‐term sequelae remain unclear. We performed a systematic literature review to investigate the incidence of pulmonary embolism (PE), microthrombi, thrombosis in situ (thromboinflammatory disease), and chronic thromboembolic pulmonary hypertension (CTEPH) during and after COVID‐19. PubMed and the World Health Organization Global Research Database were searched on May 7, 2021. Hospital cohort and database studies reporting data for ≥1000 patients and autopsy studies reporting data for ≥20 patients were included. Results were summarized descriptively. We screened 1438 records and included 41 references (32 hospital/database studies and 9 autopsy studies). The hospital/database studies reported the incidence of PE but not CTEPH, microthrombi, or thromboinflammatory disease. PE incidence varied widely (0%–1.1% of outpatients, 0.9%–8.2% of hospitalized patients, and 1.8%–18.9% of patients in intensive care). One study reported PE events occurring within 45 days after hospital discharge (incidence in discharged patients: 0.2%). Segmental arteries were generally the most common location for PE. In autopsy studies, PE, thromboinflammatory disease, and microthrombi were reported in 6%–23%, 43%–100%, and 45%–84% of deceased patients, respectively. Overall, the included studies mostly focused on PE during the acute phase of COVID‐19. The results demonstrate the challenges of identifying and characterizing vascular abnormalities using current protocols (e.g., visual computed tomography reads). Further research is needed to detect subtle pulmonary vascular abnormalities, distinguish thromboinflammatory disease from PE, optimize treatment, and assess the incidence of long‐term sequelae after COVID‐19.

Approach to the management of COVID-19 patients: When home care can represent the best practice

BACKGROUND

The pandemic that began around February 2020, caused by the viral pathogen SARS-CoV-2 (COVID-19), has still not completed its course at present in June 2022.

OBJECTIVE

The open research to date highlights just how varied and complex the outcome of the contagion can be.

METHOD

The clinical pictures observed following the contagion present variabilities that cannot be explained completely by the patient's age (which, with the new variants, is rapidly changing, increasingly affecting younger patients) nor by symptoms and concomitant pathologies (which are no longer proving to be decisive in recent cases) in relation to medium-to-long term sequelae. In particular, the functions of the vascular endothelium and vascular lesions at the pre-capillary level represent the source of tissue hypoxia and other damage, resulting in the clinical evolution of COVID-19.

RESULTS

Keeping the patient at home with targeted therapeutic support, aimed at not worsening vascular endothelium damage with early and appropriate stimulation of endothelial cells, ameliorates the glycocalyx function and improves the prognosis and, in some circumstances, could be the best practice suitable for certain patients.

CONCLUSION

Clinical information thus far collected may be of immense value in developing a better understanding of the present pandemic and future occurrences regarding patient safety, pharmaceutical care and therapy liability.

Altered fibrin network structure and fibrinolysis in intensive care unit patients with COVID-19, not entirely explaining the increased risk of thrombosis

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 infection is associated with an increased incidence of thrombosis.

OBJECTIVES

By studying the fibrin network structure of coronavirus disease 2019 (COVID-19) patients, we aimed to unravel pathophysiological mechanisms that contribute to this increased risk of thrombosis. This may contribute to optimal prevention and treatment of COVID-19 related thrombosis.

PATIENTS/METHODS

In this case-control study, we collected plasma samples from intensive care unit (ICU) patients with COVID-19, with and without confirmed thrombosis, between April and December 2020. Additionally, we collected plasma from COVID-19 patients admitted to general wards without thrombosis, from ICU patients with pneumococcal infection, and from healthy controls. Fibrin fiber diameters and fibrin network density were quantified in plasma clots imaged with stimulated emission depletion microscopy and confocal microscopy. Finally, we determined the sensitivity to fibrinolysis.

RESULTS

COVID-19 ICU patients (n = 37) and ICU patients with pneumococcal disease (n = 7) showed significantly higher fibrin densities and longer plasma clot lysis times than healthy controls (n = 7). No differences were observed between COVID-19 ICU patients with and without thrombosis, or ICU patients with pneumococcal infection. At a second time point, after diagnosis of thrombosis or at a similar time point in patients without thrombosis, we observed thicker fibers and longer lysis times in COVID-19 ICU patients with thrombosis (n = 19) than in COVID-19 ICU patients without thrombosis (n = 18).

CONCLUSIONS

Our results suggest that severe COVID-19 is associated with a changed fibrin network structure and decreased susceptibility to fibrinolysis. Because these changes were not exclusive to COVID-19 patients, they may not explain the increased thrombosis risk.

Acute complete splenic infarction secondary to COVID-19 infection

Splenic infarction in COVID-19 patients is a rare entity with few documented cases. We report a case of symptomatic complete splenic infarction and discuss COVID-19 related thrombosis, splenic infarction, diagnostic imaging for splenic infarction, and the management. Thrombotic events related to COVID-19 have been reported in unusual locations, and our case highlights an example of one such location, the splenic artery. Contrast enhanced Computed Tomography (CT) is the standard diagnostic modality and will typically reveal foci of hypo-enhancement, peripheral and wedge-shaped. CT angiography can be performed to evaluate the arteries and diagnose thrombosis. The primary treatment is aimed at addressing the underlying cause and includes supportive care. It is important that physicians consider splenic infarction as an explanation for abdominal pain in COVID-19 patients.

Stability of vitamin K antagonist anticoagulation after COVID-19 diagnosis

BACKGROUND

Coagulopathy has been reported in severely ill patients with coronavirus disease 2019 (COVID-19). It is unclear whether outpatients with COVID-19 who are treated with vitamin K antagonists (VKAs) have unstable anticoagulation.

OBJECTIVE

To assess the stability of VKA therapy in patients with COVID-19 through a case-crossover study.

METHODS

Between February and July 2020, we included patients who tested positive for COVID-19 from two anticoagulant clinics in the Netherlands. We collected international normalized ratios (INRs) determined between 26 weeks before infection and 12 weeks after. Time in therapeutic range (TTR) and the variance growth rate (VGR) were calculated within patients.

RESULTS

Fifty-one patients with COVID-19 (mean age, 84 years) were included, of whom 15 (29%) were men. Mean TTR in the 26 weeks before COVID-19 was 80% (95% confidence interval [CI], 75-85) compared to 59% (95% CI, 51-68) in the 6 weeks after infection. Mean TTR difference was -23% (95% CI, -32 to -14) with a time above therapeutic range of 38% (95% CI, 30-47) in the 6 weeks after infection. The TTR rose again to 79% (95% CI, 69-89) between 6 and 12 weeks after infection. Also, VGR increased, with a mean increase of 4.8 (95% CI, 2.1-7.5) in the 6 weeks after infection. In the 26 weeks before infection, we registered 19 of 641 (3%) of INR ≥5.0 compared with 35 of 247 (14%) in the 6 weeks after (risk ratio, 4.4; 95% CI, 2.7-7.3).

CONCLUSIONS

COVID-19 is associated with a strong decrease in TTR and in therapeutic stability in patients taking VKAs. Additional monitoring in these patients is advised to maximize therapeutic stability.

Ruling out Pulmonary Embolism in Patients with (Suspected) COVID-19-A Prospective Cohort Study

Background  Diagnostic strategies for suspected pulmonary embolism (PE) have not been prospectively evaluated in COVID-19 patients.

Methods  Prospective, multicenter, outcome study in 707 patients with both (suspected) COVID-19 and suspected PE in 14 hospitals. Patients on chronic anticoagulant therapy were excluded. Informed consent was obtained by opt-out approach. Patients were managed by validated diagnostic strategies for suspected PE. We evaluated the safety (3-month failure rate) and efficiency (number of computed tomography pulmonary angiographies [CTPAs] avoided) of the applied strategies.

Results  Overall PE prevalence was 28%. YEARS was applied in 36%, Wells rule in 4.2%, and “CTPA only” in 52%; 7.4% was not tested because of hemodynamic or respiratory instability. Within YEARS, PE was considered excluded without CTPA in 29%, of which one patient developed nonfatal PE during follow-up (failure rate 1.4%, 95% CI 0.04–7.8). One-hundred seventeen patients (46%) managed according to YEARS had a negative CTPA, of whom 10 were diagnosed with nonfatal venous thromboembolism (VTE) during follow-up (failure rate 8.8%, 95% CI 4.3–16). In patients managed by CTPA only, 66% had an initial negative CTPA, of whom eight patients were diagnosed with a nonfatal VTE during follow-up (failure rate 3.6%, 95% CI 1.6–7.0).

Conclusion  Our results underline the applicability of YEARS in (suspected) COVID-19 patients with suspected PE. CTPA could be avoided in 29% of patients managed by YEARS, with a low failure rate. The failure rate after a negative CTPA, used as a sole test or within YEARS, was non-negligible and reflects the high thrombotic risk in these patients, warranting ongoing vigilance.