Factor XI inhibition in cardiovascular disease.

Cardiovascular disease remains the leading global cause of mortality, requiring effective antithrombotic strategies to prevent thromboembolic events. Currently available therapies are effective but have inherent bleeding risks which may limit or preclude their use, particularly in patients at the highest risk of bleeding. Factor XI (FXI) inhibitors are a promising new class of anticoagulants which may mitigate the risk of bleeding while maintaining efficacy. Further, they have the potential to provide effective anticoagulation in indications where direct oral anticoagulants (DOACs) are proven less effective than vitamin K antagonists (VKAs) or when DOACs are contraindicated. The development of FXI inhibitors was based on mechanistic considerations suggesting FXI's role in thrombus formation without significantly affecting hemostasis, supported by epidemiological data and animal experiments. FXI inhibitors, including antisense oligonucleotides, monoclonal antibodies, and small­molecule inhibitors, target different stages of FXI production or activation, offering a diversity of therapeutic options with differing onset and offset of action, drug interaction potential, and renal elimination. FXI inhibitors have shown potential benefits in phase II trials, demonstrating similar or reduced bleeding rates to existing agents, including DOACs. The early termination of AZALEA­TIMI 71 (Safety and Tolerability of Abelacimab [MAA868] vs Rivaroxaban in Patients With Atrial Fibrillation) and OCEANIC­AF (A Study to Learn How Well the Study Treatment Asundexian Works and How Safe it is Compared to Apixaban to Prevent Stroke or Systemic Embolism in People With Irregular and Often Rapid Heartbeat [Atrial Fibrillation], and at Risk for Stroke) trials underscores challenges in the selection of appropriate patient populations and anticoagulant class, agent, and dose. Ongoing phase III trials including OCEANIC­STROKE (A Study to Test Asundexian for  Preventing a Stroke Caused by a Clot in Participants After an Acute Ischemic Stroke or After a High­risk Transient Ischemic Attack, a So­called Mini Stroke) and LIBREXIA trials aim to further explore the efficacy of FXI inhibitors in stroke, acute coronary syndrome, and atrial fibrillation. In conclusion, FXI inhibitors hold promise as next­generation anticoagulants, potentially addressing limitations of current therapies. Ongoing research is required to establish their place in clinical practice and address unresolved questions.

Anticoagulation for stroke prevention in atrial fibrillation and treatment of venous thromboembolism and portal vein thrombosis in cirrhosis: guidance from the SSC of the ISTH.

While advanced liver disease was previously considered to be an acquired bleeding disorder, there is increasing recognition of an associated prothrombotic state with patients being at higher risk of atrial fibrillation (AF) and stroke and venous thromboembolism (VTE) including portal vein thrombosis (PVT). We review the available literature on epidemiology, pathophysiology, and risk factors and provide guidance on anticoagulant management of these conditions in adults with cirrhosis. In patients with Child-Pugh A or B cirrhosis and AF, we recommend anticoagulation with standard-dose direct oral anticoagulants (DOACs) in accordance with cardiology guideline recommendations for patients without liver disease. In those with Child-Pugh C cirrhosis, there is inadequate evidence with respect to the benefit and risk of anticoagulation for stroke prevention in AF. In patients with cirrhosis and acute deep vein thrombosis or pulmonary embolism, we recommend anticoagulation and suggest use of either a DOAC or low-molecular-weight heparin (LMWH)/vitamin K antagonist (VKA) in Child-Pugh A or B cirrhosis and LMWH alone (or as a bridge to VKA in patients with a normal baseline international normalized ratio) in Child-Pugh C cirrhosis. We recommend anticoagulation for patients with cirrhosis and symptomatic PVT. We suggest anticoagulation for those with asymptomatic, progressing PVT and recommend continuing extended anticoagulation for liver transplant candidates with PVT.

In healthy older adults, low-dose aspirin increased incident anemia at a median 4.7 y.

SOURCE CITATION: McQuilten ZK, Thao LT, Pasricha SR, et al. Effect of low-dose aspirin versus placebo on incidence of anemia in the elderly: a secondary analysis of the Aspirin in Reducing Events in the Elderly trial. Ann Intern Med. 2023;176:913-921. 37335992.

In AF, the effects of DOACs vs. warfarin on death and stroke/systemic embolism vary by baseline CrCl level.

SOURCE CITATION: Harrington J, Carnicelli AP, Hua K, et al. Direct oral anticoagulants versus warfarin across the spectrum of kidney function: patient-level network meta-analyses from COMBINE AF. Circulation. 2023;147:1748-1757. 37042255.

Drug-drug interactions between direct oral anticoagulants and anticonvulsants and clinical outcomes: A systematic review.

Background: Direct oral anticoagulants (DOACs) are widely used in patients with atrial fibrillation and venous thromboembolism. However, DOACs have important potential drug-drug interactions (DDIs) with several classes of drugs. In particular, antiepileptic (AE) drugs may induce cytochrome P450 3A4 or P-glycoprotein. Co-administration of DOACs and AE drugs may result in lower DOAC drug levels and reduced DOAC efficacy. However, the clinical significance of such DDIs is uncertain. Objectives: The aim of this systematic review was to generate an updated review of these DDIs and their clinical relevance, given the rapidly evolving knowledge relating to DOAC and AE DDIs. Methods: We searched the MEDLINE and Embase databases for studies reporting clinical adverse outcomes (thrombotic events, bleeding events, and all-cause mortality) in patients concomitantly taking DOACs and AE drugs. Results: We retrieved 874 studies of which 15 were deemed eligible for this review, including 4 congress abstracts, 3 case reports, 2 letters to the editor, 5 retrospective cohorts, and 1 prospective cohort study. No randomized clinical trials were found. Most of the included studies reported thrombotic events, 3 studies reported major bleeding, and one study reported all-cause mortality associated with DOAC and AE drug administration. Substantial differences in the study designs did not allow for a meta-analysis to be performed. Conclusion: The current literature assessing these adverse clinical outcomes from DOAC and AE drug co-administration is limited. Although the available data point to a possible increased risk of thrombotic events, they are insufficient to draw definitive conclusions. Well-designed clinical studies are of utmost importance.

De novo phosphatidylcholine synthesis in the small intestinal epithelium is required for normal dietary lipid handling and maintenance of the mucosal barrier.

Cytidine triphosphate:phosphocholine cytidylyltransferase-α (CTα) is the rate limiting enzyme in the major pathway for de novo phosphatidylcholine (PC) synthesis. When CTα is deleted specifically in intestinal epithelial cells of adult mice (CTαIKO mice) fed a high-fat diet they present with weight loss, lipid malabsorption, and high postprandial GLP-1 levels. The current study aimed to characterize the changes that occur in the small intestines of CTαIKO mice using transcriptomics and to determine whether intestinal function could be rescued in CTαIKO mice. We found that impaired de novo PC synthesis in the gut is linked to lower abundance of transcripts related to lipid metabolism and higher abundance of transcripts related to ER stress and cell death, together with loss of goblet cells from the small intestinal epithelium. Furthermore, impaired movement of fatty acids from the intestinal lumen into enterocytes was observed in isolated intestinal sacs derived from CTαIKO mice, a model that excludes factors such as bile, gastric emptying, the nervous system, and circulating hormones. Antibiotic treatment prevented acute weight loss and normalized jejunum TG concentrations after refeeding but did not prevent ER stress or loss of goblet cells in CTαIKO mice. Dietary PC supplementation partially prevented loss of goblet cells but was unable to normalize jejunal TG concentrations after refeeding in CTαIKO mice. High postprandial plasma GLP-1 levels were present in CTαIKO mice regardless of antibiotic treatment, dietary PC content, or dietary fat content. Together, these data show that there is a specific requirement from de novo PC synthesis in maintaining small intestinal homeostasis, including dietary lipid uptake, normal hormone secretion, and barrier function.

Dual pathway inhibition for atherosclerotic cardiovascular disease: Recent advances.

Atherosclerotic cardiovascular disease (ASCVD), which includes coronary artery disease (CAD), cerebrovascular disease, and peripheral arterial disease (PAD) is associated with significant morbidity, mortality, and healthcare costs. Antiplatelet therapy has long been the mainstay of antithrombotic therapy for the prevention of first-ever and recurrent ASCVD events. More recently, however, randomized trials have demonstrated the benefits and cost-effectiveness of a dual pathway inhibition (DPI) strategy in acute and chronic ASCVD. When used in combination, aspirin and low-dose rivaroxaban work synergistically to inhibit platelet activation and thrombin generation, thereby preventing thrombus formation. Among patients with recent acute coronary syndrome (ACS), those with positive cardiac biomarkers or ST-segment elevation myocardial infarction, or a history of heart failure derive the greatest absolute benefits. Among patients with chronic ASCVD, those with involvement of two or more vascular beds, heart failure, chronic kidney disease, or diabetes derive the greatest absolute benefits. Additional trials are underway to assess the impact of DPI therapy in other populations of interest, including patients with ACS at high risk of left ventricular thrombus formation, intracranial atherosclerotic disease with recent transient ischemic attack or stroke, peripheral arterial disease with limiting claudication or post lower extremity revascularization, and advanced chronic kidney disease with ASCVD or risk factors for ASCVD. Further work is required to assess the possible added benefit of combining rivaroxaban with clopidogrel or ticagrelor instead of aspirin.

The clot thickens-enhanced integration of stroke and thrombosis training.

There is significant overlap between knowledge and its clinical application in stroke and thrombosis & vascular medicine. Formal integration of training is, however, not standard. After the hyperacute phase of management, personalized medical decisions are often needed regarding antithrombotics and anticoagulants that leverage clinical practice parameters from both disciplines with a unique emphasis on minimizing neurologic treatment complications. We completed an ad hoc survey of adult thrombosis fellowships at several North American centers. We discovered that direct integration of training programs is not prevalent, suggesting a role for more deliberate integration of training programs. We provide a framework and resources for consideration that directly improve, by design, integrated clinical experiences during training, harnessing the strengths in both stroke and thrombosis programs.

Direct oral anticoagulant dose selection: Challenging cases.

Direct oral anticoagulants (DOACs) are given in fixed doses without routine laboratory monitoring of their anticoagulant effect based on the results of pivotal phase III trials. In some of these trials, patients were randomly allocated to receive a higher or lower dose of a DOAC, whereas in others, most patients were given a standard dose and only a subset deemed to be at risk of drug accumulation was given a lower dose. Treatment guidelines recommend dosing DOACs according to the way that they were tested in the trials, but for some patients, the optimal dosing remains uncertain. One example is patients with atrial fibrillation who are thought to have an unacceptably high risk of bleeding but do not meet the guideline criteria for dose reduction. A second is patients with venous thromboembolism who have completed 3 to 6 months of anticoagulation and are eligible for extended treatment with a standard or reduced dose of DOAC. In this review, we present a case-based approach to DOAC dose selection in these two settings.

Initiation of anticoagulation in atrial fibrillation by primary care physicians: Results of a telephone survey.

BACKGROUND: Direct oral anticoagulants (DOACs) are prescribed for over 80% of patients who start anticoagulant therapy for a new diagnosis of atrial fibrillation (AF). Inappropriate DOAC prescriptions are associated with increased mortality. However, limited data exist as to what proportion of primary care physicians (PCPs) initiate anticoagulation in patients with new AF and the extent of their DOAC knowledge. MATERIAL AND METHODS: We conducted a telephone survey of randomly selected PCPs in Ontario, Canada. Our primary objective was to determine the percentage of PCPs who initiate anticoagulation in new AF patients and the proportion of patients they initiate on DOACs. Our secondary objectives were to assess PCPs' knowledge about DOACs and to identify educational opportunities to address any knowledge gaps. RESULTS: Our survey included 50 respondents. After making a new AF diagnosis, 66% of PCPs stated that they usually initiate anticoagulation themselves and 84% prescribed a DOAC at least 75% of the time. Potential DOAC knowledge gaps included: administration considerations, off-label dosing, concomitant use of acetylsalicylic acid (ASA) in stable coronary artery disease (CAD) and use in valvular AF. CONCLUSION: Most PCPs initiate anticoagulants for AF and prescribe DOACs for the vast majority of new patients. PCPs were well versed in certain aspects of DOAC prescribing, however, a number of knowledge gaps were identified. PCPs may benefit from targeted education in these areas to improve patient outcomes in AF.