Increased blood viscosity and red blood cell aggregation in patients with COVID-19.

The aim of this study was to (1) analyze blood viscosity, red blood cell (RBC) deformability, and aggregation in hospitalized patients with Coronavirus disease 19 (COVID-19); (2) test the associations between impaired blood rheology and blood coagulation; and (3) test the associations between impaired blood rheology and several indicators of clinical severity. A total of 172 patients with COVID-19, hospitalized in COVID-unit of the Internal Medicine Department (Lyon, France) participated in this study between January and May 2021. Clinical parameters were collected for each patient. Routine hematological/biochemical parameters, blood viscosity, RBC deformability and aggregation, and RBC senescence markers were measured on the first day of hospitalization. A control group of 38 healthy individuals was constituted to compare the blood rheological and RBC profile. Rotational thromboelastography was performed in 76 patients to study clot formation dynamics. Our study demonstrated that patients with COVID-19 had increased blood viscosity despite lower hematocrit than healthy individuals, as well as increased RBC aggregation. In-vitro experiments demonstrated a strong contribution of plasma fibrinogen in this RBC hyper-aggregation. RBC aggregation correlated positively with clot firmness, negatively with clot formation time, and positively with the length of hospitalization. Patients with oxygen supplementation had higher RBC aggregation and blood viscosity than those without, and patients with pulmonary lesions had higher RBC aggregation and enhanced coagulation than those without. This study is the first to demonstrate blood hyper-viscosity and RBC hyper-aggregation in a large cohort of patients with COVID-19 and describe associations with enhanced coagulation and clinical outcomes.

Presenting Characteristics, Treatment Patterns, and Outcomes among Patients with Venous Thromboembolism during Hospitalization for COVID-19.

Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). However, limited data exist on patient characteristics, treatments, and outcomes. To describe the clinical characteristics, treatment patterns, and short-term outcomes of patients diagnosed with VTE during hospitalization for COVID-19. This is a prospective multinational study of patients with incident VTE during the course of hospitalization for COVID-19. Data were obtained from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) registry. All-cause mortality, VTE recurrences, and major bleeding during the first 10 days were separately investigated for patients in hospital wards versus those in intensive care units (ICUs). As of May 03, 2020, a total number of 455 patients were diagnosed with VTE (83% pulmonary embolism, 17% isolated deep vein thrombosis) during their hospital stay; 71% were male, the median age was 65 (interquartile range, 55-74) years. Most patients (68%) were hospitalized in medical wards, and 145 in ICUs. Three hundred and seventeen (88%; 95% confidence interval [CI]: 84-91%) patients were receiving thromboprophylaxis at the time of VTE diagnosis. Most patients (88%) received therapeutic low-molecular-weight heparin, and 15 (3.6%) received reperfusion therapies. Among 420 patients with complete 10-day follow-up, 51 (12%; 95% CI: 9.3-15%) died, no patient recurred, and 12 (2.9%; 95% CI: 1.6-4.8%) experienced major bleeding. The 10-day mortality rate was 9.1% (95% CI: 6.1-13%) among patients in hospital wards and 19% (95% CI: 13-26%) among those in ICUs. This study provides characteristics and early outcomes of patients diagnosed with acute VTE during hospitalization for COVID-19. Additional studies are needed to identify the optimal strategies to prevent VTE and to mitigate adverse outcomes associated.