Evaluation of the Clinical Impact of Thromboprophylaxis in Patients With COVID-19 Following Hospital Discharge

Background: Data are limited regarding the incidence of thromboembolism post-hospital discharge among COVID-19 patients. Guidelines addressing the role of extended thromboprophylaxis for COVID-19 patients are limited and conflicting. Objective: The purpose of this study was to evaluate the incidence of post-discharge thromboembolic and bleeding events and the role of thromboprophylaxis among COVID-19 patients. Methods: A retrospective analysis was conducted of hospitalized patients with symptomatic COVID-19 infection who were discharged from a University of Colorado Health (UCHealth) hospital between March 1, 2020, and October 31, 2020. The primary outcome was objectively confirmed thromboembolism within 35 days post-discharge. The main secondary outcome was the incidence of bleeding events within 35 days post-discharge. Outcomes were compared between those who received extended prophylaxis and those who did not. Results: A total of 1171 patients met the study criteria. A total of 13 (1.1%) of patients had a documented thromboembolic event and 10 (0.9%) patients had a documented bleeding event within 35 days post-discharge. None of the 132 patients who received extended prophylaxis had a thromboembolic event compared to 13 of 1039 who did not receive extended prophylaxis (0 and 1.3%, respectively; P = .383). The incidence of bleeding was higher among patients who received extended prophylaxis compared to those who did not (3.0% vs 0.6%, P = .019). Conclusions and Relevance: These results suggest that post-discharge extended prophylaxis may be beneficial for select COVID-19 patients, while carefully weighing the risk of bleeding. Application of our findings may assist institutions in development of thromboprophylaxis protocols for discharged COVID-19 patients.

Low in-hospital mortality rate in patients with COVID-19 receiving thromboprophylaxis: data from the multicentre observational START-COVID Register

COVID-19 infection causes respiratory pathology with severe interstitial pneumonia and extra-pulmonary complications; in particular, it may predispose to thromboembolic disease. The current guidelines recommend the use of thromboprophylaxis in patients with COVID-19, however, the optimal heparin dosage treatment is not well-established. We conducted a multicentre, Italian, retrospective, observational study on COVID-19 patients admitted to ordinary wards, to describe clinical characteristic of patients at admission, bleeding and thrombotic events occurring during hospital stay. The strategies used for thromboprophylaxis and its role on patient outcome were, also, described. 1091 patients hospitalized were included in the START-COVID-19 Register. During hospital stay, 769 (70.7%) patients were treated with antithrombotic drugs: low molecular weight heparin (the great majority enoxaparin), fondaparinux, or unfractioned heparin. These patients were more frequently affected by comorbidities, such as hypertension, atrial fibrillation, previous thromboembolism, neurological disease, and cancer with respect to patients who did not receive thromboprophylaxis. During hospital stay, 1.2% patients had a major bleeding event. All patients were treated with antithrombotic drugs; 5.4%, had venous thromboembolism [30.5% deep vein thrombosis (DVT), 66.1% pulmonary embolism (PE), and 3.4% patients had DVT + PE]. In our cohort the mortality rate was 18.3%. Heparin use was independently associated with survival in patients aged ≥ 59 years at multivariable analysis. We confirmed the high mortality rate of COVID-19 in hospitalized patients in ordinary wards. Treatment with antithrombotic drugs is significantly associated with a reduction of mortality rates especially in patients older than 59 years.

Anticoagulation Changes Following Major and Clinically Relevant Nonmajor Bleeding Events in Non-valvular Atrial Fibrillation Patients

Background Bleeding events are common complications of oral anticoagulant drugs, including both warfarin and the direct oral anticoagulants (DOACs). Some patients have their anticoagulant changed or discontinued after experiencing a bleeding event, while others continue the same treatment. Differences in anticoagulation management between warfarin- and DOAC-treated patients following a bleeding event are unknown. Methods Patients with non-valvular atrial fibrillation from six anticoagulation clinics taking warfarin or DOAC therapy who experienced an International Society of Thrombosis and Haemostasis (ISTH)-defined major or clinically relevant non-major (CRNM) bleeding event were identified between 2016 and 2020. The primary outcome was management of the anticoagulant following bleeding (discontinuation, change in drug class, and restarting of same drug class). DOAC- and warfarin-treated patients were propensity matched based on the individual elements of the CHA2DS2-VASc and HAS-BLED scores as well as the severity of the bleeding event. Results Of the 509 patients on warfarin therapy and 246 on DOAC therapy who experienced a major or CRNM bleeding event, the majority of patients continued anticoagulation therapy. The majority of warfarin (231, 62.6%) and DOAC patients (201, 81.7%) restarted their previous anticoagulation. Conclusion Following a bleeding event, most patients restarted anticoagulation therapy, most often with the same type of anticoagulant that they previously had been taking.

Comparison of Higher-Than-Standard to D-Dimer Driven Thromboprophylaxis in Hospitalized Patients With COVID-19

Introduction: Coronavirus disease 2019 is a global health threat often accompanied with coagulopathy. Despite use of thromboprophylaxis in this population, thrombotic event rates are high. Materials and methods: This was a multicenter, retrospective cohort study comparing the safety and effectiveness of thromboprophylaxis strategies at 2 institutions in hospitalized patients with coronavirus disease 2019. Regimen A utilized a higher-than-standard thromboprophylaxis dosage and Regimen B received full-dose anticoagulation for any D-dimer 3 mcg/mL or greater and prophylactic for less than 3 mcg/mL. The primary outcome compared the rate of thrombotic events between treatment groups. Secondary endpoints compared rates of major or clinically relevant non-major bleeding as well as the proportion of patients in each group experiencing thrombotic events within 30 days of discharge. Results: One-hundred fifty-three patients were included in the analysis, 64 receiving Regimen A and 89 receiving Regimen B. Seven (4.6%) thrombotic events occurred, 3 (4.7%) in patients receiving Regimen A, and 4 (4.5%) in Regimen B ( P = 1.0). Twelve patients (13.5%) receiving Regimen B had a bleeding event versus 2 (3.1%) in Regimen A ( P = .04), half of which were major in each group. All patients who bled in either treatment group were receiving mechanical ventilation, and 12 of 14 were receiving full-dose anticoagulation. One patient receiving Regimen A was readmitted with a pulmonary embolism. Conclusions: In this study, the thromboprophylactic regimen impacted bleeding, but no significant difference was seen with thrombotic outcomes. Almost all patients who experienced a bleed were mechanically ventilated and receiving full-dose anticoagulation. The use of full-dose anticoagulation should be cautioned in this population without an additional indication.

COVID-19 vaccination in patients with immune thrombocytopenia

Immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by low platelet count and increased bleeding risk. COVID-19 vaccination has been described as risk factor for de novo ITP, but the effects of COVID-19 vaccination in patients with ITP are unknown. Our aims were to investigate the effects of COVID-19 vaccination in ITP patients on platelet count, bleeding complications and ITP exacerbation (any of: ≥50% decline in platelet count; or nadir platelet count <30x109/L with >20% decrease from baseline; or use of rescue therapy). Platelet counts of ITP patients and healthy controls were collected immediately before, 1 and 4 weeks after first and second vaccination. Linear mixed-effects modelling was applied to analyze platelet counts over time. We included 218 ITP patients (50.9% female, mean age 55 years and median platelet count of 106x109/L) and 200 healthy controls (60.0% female, mean age 58 years and median platelet count of 256x109/L). Platelet counts decreased by 6.3% after vaccination. We observed no difference in decrease between the groups. Thirty ITP patients (13.8%, 95%CI 9.5%-19.1%) had an exacerbation and 5 (2.2%, 95%CI 0.7%-5.3%) suffered from a bleeding event. Risk factors for ITP exacerbation were platelet count <50x109/L (OR 5.3, 95%CI 2.1-13.7), ITP treatment at time of vaccination (OR 3.4, 95%CI 1.5-8.0) and age (OR 0.96 per year, 95%CI 0.94-0.99). Our study highlights safety of COVID-19 vaccination in ITP patients and importance of close monitoring platelet counts in a subgroup of ITP patients. ITP patients with exacerbation responded well on therapy.

Evaluation of Unfractionated Heparin Dosing by Antifactor Xa During Targeted Temperature Management Post Cardiac Arrest

Purpose: To evaluate unfractionated heparin (UFH) dosing guided by antifactor Xa levels during targeted temperature management (TTM) post-cardiac arrest. Methods: Single-center, retrospective, observational study between January 1, 2014 and September 1, 2020. Patients initiated on TTM post-cardiac arrest and UFH were evaluated for inclusion. Patients included were ≥18 years of age and received weight-based UFH for ≥6 hours with 2 antifactor Xa levels drawn at target temperature. Excluded patients had no available temperature readings, received extracorporeal membrane oxygenation (ECMO) or factor Xa inhibitor (within 72 hours), or had hypertriglyceridemia or hyperbilirubinemia. The primary endpoint was to evaluate the proportion of patients that achieved a therapeutic antifactor Xa level between 0.3 and 0.7 IU/mL at steady state during TTM. Secondary endpoints included average UFH dose and average time to therapeutic antifactor Xa level at steady state; percent of first and total antifactor Xa levels subtherapeutic, therapeutic, and supratherapeutic during TTM. Results: A total of 73 patients met inclusion criteria. Of these, 21 patients achieved steady-state therapeutic antifactor Xa levels during TTM. The average time and dose to steady-state therapeutic antifactor Xa levels were 8.1 ± 4.5 hours and 9.9 ± 3.2 units/kg/hour. Overall, 61.7% of first and 47.4% of all antifactor Xa levels were supratherapeutic during TTM. Three (4.1%) patients experienced a major bleeding event. Conclusions: Guideline recommended UFH dosing, 12 or 18 units/kg/hour, during TTM resulted in more supratherapeutic antifactor Xa levels. Reduction of UFH infusion dose to 10 units/kg/hour may be required during TTM to maintain therapeutic antifactor Xa levels.

478 Clinical outcomes of patients at very high stroke risk undergoing watchman implantation

Aims Left atrial appendage occlusion (LAAO) with the Watchman device is an effective alternative to oral anticoagulation in patients with non-valvular atrial fibrillation at high thromboembolic risk. We sought to evaluate the safety and effectiveness of LAAO for stroke and bleeding prevention in patients at very high stroke risk. Methods and results Data were extracted from a prospective database of 488 AF patients who underwent LAA closure with a Watchman device. Periprocedural complications, thromboembolic (TE), and bleeding event rates among patients with a CHA2DS2-VASc ≥ 5 were reported. Predicted annual rates of TE or major bleeding events were compared to the annualized observed risk of the population. Overall, 209 patients with a CHA2DS2-VASc ≥5 (CHA2DS2-VASc: 6.0 ± 1.0; HAS-BLED: 3.7 ± 1.1) were included in the study. The mean age was 78 ± 6 years and 52.2% (n = 109) were males. Watchman implantation was successful in all patients. Overall procedure-related complication rate was 3.3% (n = 7). Two major complications were observed (1.0%): one pericardial tamponade requiring surgery and one major bleeding event at 3 days post-procedure. The incidence of minor complications was 2.3% (n = 5). Specifically, two patients experienced a pericardial effusion that required drainage and three had a groin hematoma. During a mean follow-up duration of 12 ± 5 months (193 pt/years), six TE events (2.9%/annualized rate: 3.1%) were documented after a median of 6.3 months (IQR: 2.2–9.6). Based on the estimated annual TE risk according to the CHA2DS2-VASc score (8.5%), the % risk reduction after LAAO was 63.5%. Four major bleeding events [1.9% (median time to event: 2.1 months; IQR: 1.0–3.4)] and five minor bleeding events occurred (2.5%) during follow-up. Compared to the expected rate of bleeding events as assessed by the HAS-BLED of the population (8.03%), LAAO led to a 42% reduction of bleeding risk. Conclusions In a population at very high TE risk, LAAO with the Watchman device was a safe and effective approach, and led to a 63.5% of stroke risk.

The PAR4 platelet thrombin receptor variant rs773902 does not impact the incidence of thrombotic or bleeding events in a healthy older population

Background: Protease-activated receptor 4 (PAR4) is a platelet thrombin receptor important for thrombosis and a target of anti-platelet drug development. A frequently occurring single nucleotide polymorphism (SNP; rs773902) causes a PAR4 sequence variant (NC_000019.10:p.Ala120Thr) whereby platelets from Thr120-expressing individuals are hyper-responsive to PAR4 agonists versus platelets from Ala120-expressing individuals. However, whether this enhanced platelet responsiveness translates to increased thrombotic risk or decreased bleeding risk remains unknown. Objectives: To examine the association of rs773902 with adjudicated cardiovascular events and aspirin use in a randomized trial population of healthy older individuals. Patients/Methods: We analyzed 13,547 participants in the ASPirin in Reducing Events in the Elderly (ASPREE) trial. Participants had no previous cardiovascular events at enrollment and were randomized to either 100 mg daily aspirin or placebo for a median follow-up of 4.7 years. Total genotypes were 8,761 (65%) GG (Ala120 variant), 4,303 (32%) heterozygotes, and 483 (4%) AA (Thr120 variant). Cox proportional hazard regression tested the relationship between rs773902 and thrombotic events (major adverse cardiovascular events [MACE] and ischemic stroke [IS]) and bleeding (major hemorrhage [MHEM] and intracranial bleeding [ICB]). Results: No statistically significant association was observed overall or by treatment group between rs773902 and any thrombotic or bleeding event examined. Further, there was no significant interaction between rs773902 and treatment for any of MACE, IS, MHEM, or ICB. Conclusions: This post-hoc analysis of a prospective cohort study suggests that, despite sensitizing platelet activation, the rs773902 PAR4 variant is not associated with thrombotic cardiovascular or bleeding events in a healthy older population.

Anticoagulation Use and Outcomes Among Patients with Atrial Fibrillation and Von Willebrand Disease

Intro: Von Willebrand disease (VWD) is a coagulopathy caused by deficiency or dysfunction of von Willebrand factor (VWF), resulting in prolonged and excessive bleeding. Patients are advised to avoid aspirin (ASA), P2Y12 inhibitors, or anticoagulation (AC) so as not to exacerbate this condition. However, typical treatment for atrial fibrillation (AF) includes anticoagulation, particularly if the risk of stroke by CHA 2DS 2-VASC score is 2+. Current recommendations suggest giving necessary antiplatelet (AP) or AC therapy over no treatment with assessment of bleeding risk throughout the course. However, this is a conditional recommendation based on low certainty in evidence, and there are no specific guidelines on treating AF in patients with VWD. This study aims to assess anticoagulation use, bleeding risk, and stroke risk in patients with VWF and AF. Methods: We conducted an IRB-approved analysis of coded data from institutional electronic medical records to select patients with diagnosis of VWD, low ristocetin cofactor level, or any abnormal VWF panel as well as patients with diagnosis of AF or atrial flutter. Three hundred and forty patients met criteria. Patients were manually screened for inclusion criteria and excluded for inaccurate diagnosis or insufficient data. Eighty-nine patients were included in the analysis. Primary endpoint was rate of major bleeding defined by ISTH criteria while on AC or AP. Categorical data were tested using the Fisher exact test at the nominal 0.05 two-sided significance level, and all person-time comparisons are made against the rate of bleeding on AC alone. Results: Most patients were female (64.0%; 57/89), and 28.1% (25/89) were deceased at the time of data collection. Date of diagnosis of AF ranged from 1980-2020. 42.7% (38/89) of patients were ever prescribed ASA, 43.8% (39/89) a P2Y12 inhibitor, 56.2% (50/89) AC, and 23.6% (21/89) had never been prescribed AP or AC. Of patients with a CHA 2DS 2-VASC of 2+, 57.5% (46/80) were ever prescribed AC. 32.0% (16/50) of patients ever prescribed AC and 25.6% (10/39) patients never prescribed AC had at least one major bleeding event (p=0.428). The rate of major bleeding on AC alone was 8.9 events per 100 person-years (32 events/359.2 years), 10.2 events per 100 person-years on AP alone (41 events/402.3 years) (p=0.572), and 1.06 events per 100 person-years (8 events/757.47 years) in patients never prescribed AC or AP (p=<0.0001). Notably, the rate of major bleeding on AC and AP together was 28.07 events per 100 person-years (23 events/81.94 years) (p=<0.0001) occurring in 7 patients, 6 of whom also had a diagnosis of acute coronary syndrome (ACS). Length of time to first major bleed is shown in Figure 1. 16.9% (15/89) of patients had thromboembolic strokes after diagnosis of AF, and 53.3% (8/15) of those strokes occurred when patients were not prescribed AC. Discussion: This retrospective observational study over 40 years characterizes AC and AP use in patients with VWD and AF. Only 57.5% of patients with CHA 2DS 2-VASC of 2+ received standard of care AC despite conditional recommendations to give necessary anticoagulation to patients with VWD. In parallel with the general population, AC use significantly increases the rate of major bleeding in patients with VWD, but there was no difference in bleeding rate between standard AC and AP monotherapy. However, major bleeding rates were notably elevated in patients prescribed concomitant AC and AP which most commonly occurred in the setting of ACS. This analysis is limited by its retrospective nature, the lack of granular details in the coded database, and incomplete data in older charts. Overall, these data do not support the use of AP monotherapy over standard AC to reduce bleeding rates for patients with VWD and AF. Additionally, AC and AP co-administration should be avoided due to high rates of major bleeding, but more studies are required to understand AP and AC strategies in patients with VWD, AF, and ACS. Although the rate of major bleeding is elevated with AC use in patients with VWD, there is no difference in lifetime prevalence of major bleeding events by AC vs no AC use. Finally, over half of thromboembolic strokes occurred when not prescribed AC. Shared decision-making around stroke and bleeding risk is advised in considering AC use for AF in patients with VWD. Prospective studies should further evaluate the risk of major bleeding and stroke in patients with VWD and AF on standard AC vs no AC. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Outcomes of Direct Oral Anticoagulants with Aspirin Versus Warfarin with Aspirin for Atrial Fibrillation and/or Venous Thromboembolic Disease

Introduction The direct oral anticoagulants (DOACs) including apixaban, dabigatran, edoxaban, and rivaroxaban are increasingly utilized for the management of venous thromboembolic disease (VTE) and/or non-valvular atrial fibrillation (NVAF). Adding aspirin (ASA) to warfarin or DOAC therapy increases bleeding risk. Patients on combination therapy with ASA and an anticoagulant were not well represented in clinical trials comparing DOACs to warfarin. We sought to compare bleeding and thrombotic outcomes with DOACs and ASA compared to warfarin and ASA in a non-trial setting. Methods We conducted a retrospective registry-based cohort study of adults on DOAC or warfarin therapy for VTE and/or NVAF. Warfarin treated patients were followed by six anticoagulation clinics. Four out of the six clinics contributed data on their patients that were on DOACs in the Michigan Anticoagulation Quality Improvement Initiative (MAQI 2) from January 2009 to June 2021. Patients were excluded if they had a history of heart valve replacement, recent myocardial infarction, or less than 3 months of follow-up. Two propensity matched cohorts (warfarin+ASA vs DOAC+ASA) of patients were analyzed based on ASA use at the time of study enrollment. The primary outcome was any new bleeding event. Secondary outcomes included new episodes of arterial or venous thrombosis, bleeding event type (major, fatal, life threatening, central nervous system, and non-major bleeding), emergency room visits, hospitalizations, transfusions, and death. Random chart audits were done to confirm the accuracy of the abstracted data. Event rates were compared using Poisson regression. Results We identified a total of 1,139 patients on DOACs plus ASA and 4,422 patients on warfarin plus ASA. After propensity matching, we compared two groups of 1,114 matched patients. DOAC treated patients were predominately on apixaban (62.3%) and rivaroxaban (30.4%), most often at therapeutic doses (Table 1). Patients were largely (90.5%) on low dose ASA (≤ 100 mg). Patient demographics, co-morbidities, indication for anticoagulation, history of bleeding or clotting, medications, and duration of follow-up were well-balanced after matching. Patients were followed for a median of 11.7 months (interquartile range 4.4 and 34 months). Patients treated with DOAC+ASA had 2.4 thrombotic events per 100 patient years compared to 2.2 thrombotic events per 100 patient years with warfarin+ASA (P=0.78). There were no significant differences observed between groups by thrombotic subtype (stroke, transient ischemic attack, pulmonary embolism, deep vein thrombosis, table 1). Bleeding was also similar with 30.1 bleeding events per 100 patient years with DOAC+ASA compared to 27.8 bleeds per 100 patient years with warfarin+ASA (P=0.24). There were no significant differences by bleeding subtype (table 1). Hospitalizations for clotting occurred less frequently with DOAC+ASA (0.9 hospitalizations per 100 patient years) compared to warfarin+ASA (1.7 hospitalizations per 100 patient years, P=0.03). Mortality, transfusions, and healthcare utilization were otherwise similar between the two groups. Conclusions For patients on a DOAC versus warfarin with ASA for atrial fibrillation and/or venous thromboembolic disease without a recent myocardial infarction or heart valve replacement, bleeding and thrombotic outcomes were similar. Figure 1 Figure 1. Disclosures Kaatz: Gilead: Consultancy; CSL Behring: Consultancy; Novartis: Consultancy; Bristol Myer Squibb: Consultancy, Research Funding; Pfizer: Consultancy; Alexion: Consultancy; Janssen: Consultancy, Research Funding; Osmosis Research: Research Funding. Kline-Rogers: Janssen: Consultancy; American College of Physicians: Consultancy. Sood: Bayer: Consultancy. Froehlich: Merck: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Boehringer-Ingelheim: Consultancy; Pfizer: Consultancy; Blue Cross Blue Shield of Michigan: Research Funding; Fibromuscular Disease Society of America: Research Funding. Barnes: National Certification Board of Anticoagulation Providers: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Acelis: Consultancy; AMAG Pharmaceuticals: Consultancy; Connected Health: Consultancy; Blue Cross Blue Shield of Michigan: Research Funding; AC Forum: Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy; Bristol-Myers Squibb: Consultancy.