Clinical characteristics and outcomes of venous thromboembolism in patients hospitalized for COVID-19: Systematic review and meta-analysis

COVID-19-Associated Thrombotic Complication: Is It Pulmonary Embolism or In Situ Thrombosis?

Objectives

Acute pulmonary embolism is a protentional fatal complication of COVID-19. The aim of this study is to investigate whether pulmonary embolism is due to thrombus migration from the venous circulation to the pulmonary arteries or due to local thrombus formation secondary to local inflammation. This was determined by looking at the distribution of pulmonary embolism in relation to lung parenchymal changes in patients with COVID-19 pneumonia.

Methods

Retrospectively, we identified pulmonary computed tomography angiography (CTPA) of patients admitted to the Royal Hospital between November 1st, 2020, and October 31, 2021, with a confirmed diagnosis of COVID-19. The CTPAs were examined for the presence of pulmonary embolism and the distribution of the pulmonary embolism in relation with lung parenchymal changes.

Results

A total of 215 patients admitted with COVID-19 pneumonia had CTPA. Out of them, 64 patients had pulmonary embolisms (45 men and 19 women; mean age: 58.4 years with a range of 36-98 years). The prevalence of pulmonary embolism (PE) was 29.8% (64/215). Pulmonary embolism was more frequently seen in the lower lobes. 51 patients had PE within the diseased lung parenchyma and 13 patients had PE within normal lung parenchyma.

Conclusion

The strong association between pulmonary artery embolism and lung parenchymal changes in patients admitted with COVID-19 pneumonia suggests local thrombus formation.

COVID-19 patients with acute pulmonary embolism have a higher mortality risk: systematic review and meta-analysis based on Italian cohorts

BACKGROUND

Acute pulmonary embolism has been recognized as a frequent complication of COVID-19 infection influencing the clinical course and outcomes of these patients.

OBJECTIVES

We performed a systematic review and meta-analysis to evaluate the mortality risk in COVID-19 Italian patients complicated by acute pulmonary embolism in the short-term period.

METHODS

The study was performed in accordance with the Preferred Report Items for Systematic Reviews and Meta-analyses guidelines. PubMed-MEDLINE and Scopus databases were systematically searched for articles, published in the English language and enrolling Italian cohorts with confirmed COVID-19 infection from inception through 20 October 2021. Mortality risk data were pooled using the Mantel-Haenszel random effects models with odds ratio as the effect measure with 95% confidence interval. Heterogeneity among studies was assessed using Higgins and Thomson I2 statistic.

RESULTS

Eight investigations enrolling 1.681 patients (mean age 64.9 years, 1125 males) met the inclusion criteria and were considered for the analysis. A random-effect model showed that acute pulmonary embolism was present in 19.0% of Italian patients with COVID-19 infection. Moreover, these patients were at higher mortality risk compared with those without (odds ratio: 1.76, 95% confidence interval: 1.26-2.47, P  = 0.001, I2  = 0%). Sensitivity analysis confirmed yielded results.

CONCLUSION

In Italian patients with COVID-19 infection, acute pulmonary embolism was present in about one out of five and significantly associated with a higher mortality risk in the short-term period. The identification of acute pulmonary embolism in these patients remains critical to promptly identify vulnerable populations who would require prioritization in treatment and prevention and close monitoring.

Predictors of venous thromboembolism in COVID-19 patients: results of the COVID-19 Brazilian Registry

Previous studies that assessed risk factors for venous thromboembolism (VTE) in COVID-19 patients have shown inconsistent results. Our aim was to investigate VTE predictors by both logistic regression (LR) and machine learning (ML) approaches, due to their potential complementarity. This cohort study of a large Brazilian COVID-19 Registry included 4120 COVID-19 adult patients from 16 hospitals. Symptomatic VTE was confirmed by objective imaging. LR analysis, tree-based boosting, and bagging were used to investigate the association of variables upon hospital presentation with VTE. Among 4,120 patients (55.5% men, 39.3% critical patients), VTE was confirmed in 6.7%. In multivariate LR analysis, obesity (OR 1.50, 95% CI 1.11-2.02); being an ex-smoker (OR 1.44, 95% CI 1.03-2.01); surgery ≤ 90 days (OR 2.20, 95% CI 1.14-4.23); axillary temperature (OR 1.41, 95% CI 1.22-1.63); D-dimer ≥ 4 times above the upper limit of reference value (OR 2.16, 95% CI 1.26-3.67), lactate (OR 1.10, 95% CI 1.02-1.19), C-reactive protein levels (CRP, OR 1.09, 95% CI 1.01-1.18); and neutrophil count (OR 1.04, 95% CI 1.005-1.075) were independent predictors of VTE. Atrial fibrillation, peripheral oxygen saturation/inspired oxygen fraction (SF) ratio and prophylactic use of anticoagulants were protective. Temperature at admission, SF ratio, neutrophil count, D-dimer, CRP and lactate levels were also identified as predictors by ML methods. By using ML and LR analyses, we showed that D-dimer, axillary temperature, neutrophil count, CRP and lactate levels are risk factors for VTE in COVID-19 patients.

Prevalence of Acute Pulmonary Embolism at Autopsy in Patients With COVID-19

To date, the actual prevalence of acute pulmonary embolism (PE) in patients with SARS-CoV-2 infection remains unknown, as systematic screening for PE is cumbersome. We performed a systematic review and meta-analysis on autoptic data to estimate the prevalence of histopathologic findings of acute PE and its relevance as a cause of death on patients with COVID-19. We searched MEDLINE-PubMed and Scopus to locate all articles published in the English language, up to August 10, 2021, reporting the autoptic prevalence of acute PE and evaluating PE as the underlying cause of death in patients with COVID-19. The pooled prevalence for both outcomes was calculated using a random-effects model and presenting the related 95% confidence interval (CI). Statistical heterogeneity was measured using the Higgins I² statistic. We analyzed autoptic data of 749 patients with COVID-19 (mean age 63.4 years) included in 14 studies. In 10 studies, based on 526 subjects (mean age 63.8 years), a random-effect model revealed that autoptic acute PE findings were present in 27.5% of cases (95% CI 15.0 to 45.0%, I² 89.9%). Conversely, in 429 COVID-19 subjects (mean age 64.0 years) enrolled in 9 studies, acute PE was the underlying cause of death in 19.9% of cases (95% CI 11.0 to 33.3%, I² 83.3%). Autoptic findings of acute PE in patients with COVID-19 are present in about 30% of subjects, whereas a venous thromboembolic event represents the underlying cause of death in about 1 of 4 patients.

Clinical features of thrombosis and bleeding in COVID-19

Infection with the SARS-CoV-2 virus, resulting in COVID-19 disease has presented a unique scenario associated with high thrombotic rates. The risk of venous thrombosis is some 3-6 fold higher than for patients admitted to hospital for other indications and for patients who have thrombosis, mortality appears increased. Thrombosis may be a presenting feature of COVID-19. Pulmonary thrombi are the most frequent events, some related to deep vein thrombosis, but also in situ micro- and macrovascular thrombosis. Other venous thromboses include catheter and circuit-associated in patients requiring haemofiltration and ECMO. Arterial thrombosis is less commonly documented, with 3% of ICU patients having major arterial strokes and up to 9% myocardial infarction, which is likely multifactorial. Risk factors for thrombosis above those already documented in hospital settings include duration of COVID-19 symptoms before admission to hospital. Laboratory parameters associated with higher thrombotic risk include higher D-dimer, low fibrinogen and low lymphocyte count, with higher FVIII and von Willebrand factor levels indicative of more severe COVID-19 infection. All patients should receive thromboprophylaxis when admitted with COVID-19 infection, but the dose and length of treatment still remain debated. Treatment for thrombosis remains as per standard VTE guidelines, but adjustments may be required depending on other factors relevant to the patient admission.

Predictors and mortality risk of venous thromboembolism in patients with COVID-19: systematic review and meta-analysis of observational studies

Introduction:

Novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection resulting in COVID-19 disease is associated with widespread inflammation and a prothrombotic state, resulting in frequent venous thromboembolic (VTE) events. It is currently unknown whether anticoagulation is protective for VTE events. Therefore, we conducted a systematic review to identify predictors of VTE in COVID-19.

Methods:

We searched PubMed, EMBASE, Google Scholar, and Ovid databases for relevant observational studies of VTE in COVID-19 disease. The effect size for predictors of VTE was calculated using a random-effects model and presented as forest plots. Heterogeneity among studies was expressed as Q statistics and I². Bias was assessed using the Newcastle Ottawa Scale for all identified observational studies. Publication bias was assessed with funnel plot analysis.

Results:

We identified 28 studies involving 6053 patients with suspected or confirmed COVID-19. The overall pooled prevalence of VTE events was 20.7%. Male sex was associated with a higher risk of VTE events, whereas prior history of VTE, smoking, and cancer were not. VTE events were significantly higher in severely ill patients, mechanically ventilated patients, those requiring intensive care admission, and those with a low PaO₂/FiO₂ ratio (P/F ratio). Chronic comorbidities, including cardiovascular disease, heart failure, renal disease, and pulmonary disease, did not increase the risk of VTE events. Patients with VTE had higher leukocyte counts and higher levels of D-dimer, C-reactive protein, and procalcitonin. The occurrence of VTE was associated with increased length of stay but did not impact mortality. Therapeutic and prophylactic doses of anticoagulation were not protective against VTE.

Conclusion:

VTE in COVID-19 is associated with male gender and severe disease but not with traditional risk factors for VTE. The occurrence of VTE does not appear to be mitigated by either prophylactic or therapeutic anticoagulation. The occurrence of VTE in this population is associated with an increased length of stay but does not appear to impact mortality.

Pulmonary Embolism in Hospitalized Patients with COVID-19: A Multicenter Study

Background

Pulmonary embolism (PE) commonly complicates SARS-CoV-2 infection, but incidence and mortality reported in single-center studies, along with risk factors, vary.

Purpose

To determine the incidence of PE in patients with COVID-19 and its associations with clinical and laboratory parameters.

Materials and Methods

In this HIPAA-compliant study, electronic medical records were searched retrospectively for demographic, clinical, and laboratory data and outcomes among patients with COVID-19 admitted at four hospitals from March through June 2020. PE found at CT pulmonary angiography and perfusion scintigraphy was correlated with clinical and laboratory parameters. The d-dimer level was used to predict PE, and the obtained threshold was externally validated among 85 hospitalized patients with COVID-19 at a fifth hospital. The association between right-sided heart strain and embolic burden was evaluated in patients with PE undergoing echocardiography.

Results

A total of 413 patients with COVID-19 (mean age, 60 years ± 16 [standard deviation]; age range, 20–98 years; 230 men) were evaluated. PE was diagnosed in 102 (25%; 95% CI: 21, 29) of 413 hospitalized patients with COVID-19 who underwent CT pulmonary angiography or perfusion scintigraphy. PE was observed in 21 (29%; 95% CI: 19, 41) of 73 patients in the intensive care unit (ICU) versus 81 (24%; 95% CI: 20, 29) of 340 patients who were not in the ICU (P = .37). PE was associated with male sex (odds ratio [OR], 1.74; 95% CI: 1.1, 2.8; P = .02); smoking (OR, 1.86; 95% CI: 1.0, 3.4; P = .04); and increased d-dimer (P < .001), lactate dehydrogenase (P < .001), ferritin (P = .001), and interleukin-6 (P = .02) levels. Mortality in hospitalized patients was similar between patients with PE and those without PE (14% [13 of 102]; 95% CI: 8, 22] vs 13% [40 of 311]; 95% CI: 9, 17; P = .98), suggesting that diagnosis and treatment of PE were not associated with excess mortality. The d-dimer levels greater than 1600 ng/mL [8.761 nmol/L] helped predict PE with 100% sensitivity and 62% specificity in an external validation cohort. Embolic burden was higher in patients with right-sided heart strain among the patients with PE undergoing echocardiography (P = .03).

Conclusion

Pulmonary embolism (PE) incidence was 25% in patients hospitalized with COVID-19 suspected of having PE. A d-dimer level greater than 1600 ng/mL [8.761 nmol/L] was sensitive for identification of patients who needed CT pulmonary angiography.

© RSNA, 2021

Online supplemental material is available for this article.

See also the editorial by Ketai in this issue.