Background: The prevalence of venous thromboembolic event (VTE) and arterial thromboembolic event (ATE) thromboembolic events in patients with COVID-19 remains largely unknown.Methods: In this meta-analysis, we systematically searched for observational studies describing the prevalence of VTE and ATE in COVID-19 up to 30 September 2020.Results: We analysed findings from 102 studies (64 503 patients). The frequency of COVID-19-related VTE was 14.7% (95% CI 12.1% to 17.6%, I²=94%; 56 studies; 16 507 patients). The overall prevalence rates of pulmonary embolism (PE) and leg deep vein thrombosis were 7.8% (95% CI 6.2% to 9.4%, I²=94%; 66 studies; 23 117 patients) and 11.2% (95% CI 8.4% to 14.3%, I²=95%; 48 studies; 13 824 patients), respectively. Few were isolated subsegmental PE. The VTE prevalence was significantly higher in intensive care unit (ICU) (23.2%, 95% CI 17.5% to 29.6%, I²=92%, vs 9.0%, 95% CI 6.9% to 11.4%, I²=95%; p_interaction<0.0001) and in series systematically screening patients compared with series testing symptomatic patients (25.2% vs 12.7%, p_interaction=0.04). The frequency rates of overall ATE, acute coronary syndrome, stroke and other ATE were 3.9% (95% CI 2.0% to to 3.0%, I²=96%; 16 studies; 7939 patients), 1.6% (95% CI 1.0% to 2.2%, I²=93%; 27 studies; 40 597 patients) and 0.9% (95% CI 0.5% to 1.5%, I²=84%; 17 studies; 20 139 patients), respectively. Metaregression and subgroup analyses failed to explain heterogeneity of overall ATE. High heterogeneity limited the value of estimates.Conclusions: Patients admitted in the ICU for severe COVID-19 had a high risk of VTE. Conversely, further studies are needed to determine the specific effects of COVID-19 on the risk of ATE or VTE in less severe forms of the disease.

Coronavirus disease 2019 (COVID-19), currently a worldwide pandemic, is a viral illness caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The suspected contribution of thrombotic events to morbidity and mortality in COVID-19 patients has prompted a search for novel potential options for preventing COVID-19-associated thrombotic disease. In this article by the Global COVID-19 Thrombosis Collaborative Group, we describe novel dosing approaches for commonly used antithrombotic agents (especially heparin-based regimens) and the potential use of less widely used antithrombotic drugs in the absence of confirmed thrombosis. Although these therapies may have direct antithrombotic effects, other mechanisms of action, including anti-inflammatory or antiviral effects, have been postulated. Based on survey results from this group of authors, we suggest research priorities for specific agents and subgroups of patients with COVID-19. Further, we review other agents, including immunomodulators, that may have antithrombotic properties. It is our hope that the present document will encourage and stimulate future prospective studies and randomized trials to study the safety, efficacy, and optimal use of these agents for prevention or management of thrombosis in COVID-19. ^* Drs. Bikdeli and Madhavan contributed equally to this manuscript.

Rationale: The relationship between the initial treatment strategy and survival in pulmonary arterial hypertension (PAH) remains uncertain. Objectives: To evaluate the long-term survival of patients with PAH categorized according to the initial treatment strategy. Methods: A retrospective analysis of incident patients with idiopathic, heritable, or anorexigen-induced PAH enrolled in the French Pulmonary Hypertension Registry (January 2006 to December 2018) was conducted. Survival was assessed according to the initial strategy: monotherapy, dual therapy, or triple-combination therapy (two oral medications and a parenteral prostacyclin). Measurements and Main Results: Among 1,611 enrolled patients, 984 were initiated on monotherapy, 551 were initiated on dual therapy, and 76 were initiated on triple therapy. The triple-combination group was younger and had fewer comorbidities but had a higher mortality risk. The survival rate was higher with the use of triple therapy (91% at 5 yr) as compared with dual therapy or monotherapy (both 61% at 5 yr) (P < 0.001). Propensity score matching of age, sex, and pulmonary vascular resistance also showed significant differences between triple therapy and dual therapy (10-yr survival, 85% vs. 65%). In high-risk patients (n = 243), the survival rate was higher with triple therapy than with monotherapy or dual therapy, whereas there was no difference between monotherapy and double therapy. In intermediate-risk patients (n = 1,134), survival improved with an increasing number of therapies. In multivariable Cox regression, triple therapy was independently associated with a lower risk of death (hazard ratio, 0.29; 95% confidence interval, 0.11–0.80; P = 0.017). Among the 148 patients initiated on a parenteral prostacyclin, those on triple therapy had a higher survival rate than those on monotherapy or dual therapy. Conclusions: Initial triple-combination therapy that includes parenteral prostacyclin seems to be associated with a higher survival rate in PAH, particularly in the youngest high-risk patients.

This position paper provides a comprehensive guide for optimal follow-up of patients with acute pulmonary embolism (PE), covering multiple relevant aspects of patient counselling. It serves as a practical guide to treating patients with acute PE complementary to the formal 2019 European Society of Cardiology guidelines developed with the European Respiratory Society. We propose a holistic approach considering the whole spectrum of serious adverse events that patients with acute PE may encounter on the short and long run. We underline the relevance of assessment of modifiable risk factors for bleeding, of acquired thrombophilia and limited cancer screening (unprovoked PE) as well as a dedicated surveillance for the potential development of chronic thromboembolic pulmonary hypertension as part of routine practice; routine testing for genetic thrombophilia should be avoided. We advocate the use of outcome measures for functional outcome and quality of life to quantify the impact of the PE diagnosis and identify patients with the post-PE syndrome early. Counselling patients on maintaining a healthy lifestyle mitigates the risk of the post-PE syndrome and improves cardiovascular prognosis. Therefore, we consider it important to discuss when and how to resume sporting activities soon after diagnosing PE. Additional patient-relevant topics that require Focused counselling are travel and birth control.

In patients with active cancer and venous thromboembolism, whether extended treatment with a reduced dose of an oral anticoagulant is effective in preventing recurrent thromboembolic events and decreasing bleeding is unclear. We conducted a randomized, double-blind, noninferiority trial with blinded central outcome adjudication. Consecutive patients with active cancer and proximal deep-vein thrombosis or pulmonary embolism who had completed at least 6 months of anticoagulant therapy were randomly assigned in a 1:1 ratio to receive oral apixaban at a reduced (2.5 mg) or full (5.0 mg) dose twice daily for 12 months. The primary outcome was centrally adjudicated fatal or nonfatal recurrent venous thromboembolism, assessed in a noninferiority analysis (margin of 2.00 for the upper boundary of the 95% confidence interval of the subhazard ratio). The key secondary outcome was clinically relevant bleeding, assessed in a superiority analysis. A total of 1766 patients underwent randomization at a median time since the index event of 8.0 months (interquartile range, 6.5 to 12.6); 866 patients were assigned to the reduced-dose group, and 900 to the full-dose group. The median treatment duration was 11.8 months (interquartile range, 8.3 to 12.1). Recurrent venous thromboembolism occurred in 18 patients (cumulative incidence, 2.1%) in the reduced-dose group and in 24 (cumulative incidence, 2.8%) in the full-dose group (adjusted subhazard ratio, 0.76; 95% confidence interval [CI], 0.41 to 1.41; P = 0.001 for noninferiority). Clinically relevant bleeding occurred in 102 patients (cumulative incidence, 12.1%) in the reduced-dose group and in 136 (cumulative incidence, 15.6%) in the full-dose group (adjusted subhazard ratio, 0.75; 95% CI, 0.58 to 0.97; P = 0.03). Mortality was 17.7% in the reduced-dose group and 19.6% in the full-dose group (adjusted hazard ratio, 0.96; 95% CI, 0.86 to 1.06). Extended anticoagulation with reduced-dose apixaban was noninferior to full-dose apixaban for the prevention of recurrent venous thromboembolism in patients with active cancer. The reduced dose led to a lower incidence of clinically relevant bleeding complications than the full dose. (Funded by the Bristol-Myers Squibb-Pfizer Alliance; API-CAT ClinicalTrials.gov number, NCT03692065.).