A comparison of the effects of NOAC and VKA therapy on the incidence of dementia in patients with atrial fibrillation: A systematic review and meta-analysis

Atrial fibrillation (AF) patients are more susceptible to dementia, but the results about the effect of oral anticoagulants (OACs) on the risk of dementia are not consistent. We hypothesize that OAC is associated with a reduced risk of dementia with AF and that nonvitamin K antagonist oral anticoagulants (NOAC) are superior to vitamin K antagonists (VKA). Four databases were systematically searched until July 1, 2022. Two reviewers independently selected literature, evaluated quality, and extracted data. Data were examined using pooled hazard ratios (HRs) and 95% confidence intervals (CIs). Fourteen research studies involving 910 patients were enrolled. The findings indicated that OACs were associated with a decreased risk of dementia (pooled HR: 0.68, 95% CI: 0.55-0.82, I2  = 87.7%), and NOACs had a stronger effect than VKAs (pooled HR: 0.87, 95% CI: 0.79-0.95, I2  = 72%), especially in participants with a CHA2DS2VASc score ≥ 2 (pooled HR: 0.85, 95% CI: 0.72-0.99). Subgroup analysis demonstrated no statistical significance among patients aged <65 years old (pooled HR: 0.83, 95% CI: 0.64-1.07), patients in "based on treatment" studies (pooled HR: 0.89, 95% CI: 0.75-1.06), or people with no stroke background (pooled HR: 0.90, 95% CI: 0.71-1.15). This analysis revealed that OACs were related to the reduction of dementia incidence in AF individuals, and NOACs were better than VKAs, remarkably in people with a CHA2DS2VASc score ≥ 2. The results should be confirmed by further prospective studies, particularly in patients in "based on treatment" studies aged <65 years old with a CHA2DS2VASc score < 2 or without a stroke background.

A Narrative Review of Nonvitamin K Antagonist Oral Anticoagulant Use in Secondary Stroke Prevention

The prevalence of atrial fibrillation (AF), the most common cardiac arrhythmia, increases with age, predisposing elderly patients to an increased risk of embolic stroke. With an increasingly aged population the number of people who experience a stroke every year, overall global burden of stroke, and numbers of stroke survivors and related deaths continue to increase. Anticoagulation with vitamin K antagonists (VKAs) reduces the risk of ischemic stroke in patients with AF; however, increased bleeding risk is well documented, particularly in the elderly. Consequently, VKAs have been underused in the elderly. Alternative anticoagulants may offer a safer choice, particularly in patients who have experienced previous stroke. The aim of this narrative review is to examine available evidence for the effective treatment of patients with AF and previous cerebral vascular events with non-VKA oral anticoagulants, including the most appropriate time to start or reinitiate treatment after a stroke, systemic embolism, or clinically relevant bleed. For patients with AF treated with oral anticoagulants it is important to balance increased protection against future stroke/systemic embolism and reduced risk of major bleeding events. For patients with AF who have previously experienced a cerebrovascular event, the use of oral anticoagulants alone also appears more effective than low-molecular weight heparin (LMWH) alone or LMWH followed by oral anticoagulants. Available data suggest that significant reduction in stroke, symptomatic cerebral bleeding, and major extracranial bleeding within 90 days from acute stroke can be achieved if oral anticoagulation is initiated at 4-14 days from stroke onset.

Reversal Strategies for Newer Oral Anticoagulants

Nonvitamin K antagonist oral anticoagulants have advantages compared with warfarin, but both types of anticoagulants come with uncertainty about how best to manage life-threatening bleeding events, urgent surgeries, and invasive procedures. Nurse practitioners and physician assistants may need to manage such emergency situations in the critical care setting. Achieving hemostasis quickly is key, and efforts to do so have relied mainly on blood products. Targeted reversal agents are in clinical development and one, idarucizumab, which reverses dabigatran anticoagulation, has been approved. Current options for managing events and urgent procedures in anticoagulated patients are discussed in this article, with a focus on specific reversal agents.

Anticoagulation after coronary stenting: a systemic review

Introduction or background

Anticoagulant therapy is mainly used to prevent patients from suffering coronary and systemic thromboembolism after stenting. Many studies have been done to formulate an optimized regimen of a post-PCI or long-time anticoagulant therapy. Recent advances in the selection and duration of anticoagulant agents will be conducive to the management of patients who are considered to need anticoagulant therapy after stenting.

Sources of data

Key recent published literature, including international guidelines and relevant reviews.

Areas of agreement

Anticoagulant therapy has been acknowledged to improve the prognosis of patients after stenting by reducing the risk of coronary and systemic thromboembolism.

Areas of controversy

Firstly, the benefit-risk ratio of post-PCI parenteral anticoagulation to prevent stent thrombosis locally in the coronary artery is still unclear. Secondly, the efficacy and safety of bivalirudin deserve to be discussed. Furthermore, the recommendation to use long-time oral anticoagulant therapy to prevent systemic thromboembolism after stenting should also be emphasized.

Growing points

Studies of anticoagulant therapy in patients after stenting add to the understanding of an optimized anticoagulant regimen and contribute to improving clinical outcomes.

Areas for developing research

The safety and efficacy of bivalirudin, a direct thrombin inhibitor, need to be further investigated by more large-scale randomized clinical trials.Based on the widespread use of ticagrelor and prasugrel for patients who need long-time oral anticoagulant therapy, further study is needed to find an optimal strategy that balances the risk of bleeding and ischemic events after coronary stenting.

Nonvitamin K antagonist oral anticoagulant use in patients with renal impairment

The nonvitamin K antagonist oral anticoagulants (NOACs), also referred to as direct oral anticoagulants (DOACs), dabigatran, apixaban, edoxaban, and rivaroxaban, have emerged as effective alternatives to vitamin K antagonists (VKAs) across several indications, including the prevention of stroke and systemic embolism (SSE) in patients with atrial fibrillation (AF) and the treatment of venous thromboembolism (VTE). Their use in patients with renal impairment is of particular importance, given the prevalence of renal dysfunction in the indicated populations and the impact of renal function on the metabolism of the NOACs. This publication reviews the pharmacokinetic/pharmacodynamic properties of the NOACs and clinical trial results for patients with renal impairment within the AF and VTE indications. Pharmacokinetic/pharmacodynamic data show the NOACs are dependent on renal clearance to varying extents. Relative to VKAs, the efficacy and safety of the NOACs is preserved in patients with moderate renal impairment. The dosing recommendations for patients with renal impairment differ depending on the NOAC, whereby some of the NOACs require dose reductions based solely on renal function, while others require consideration of additional criteria. However, despite these specific dosing recommendations, emerging real-world evidence suggests patients are not being dosed appropriately, indicating a possible knowledge gap. Adherence to recommended dosing algorithms has implications on the optimal efficacy and safety of the NOACs. To this end, renal function should be assessed in patients on a NOAC, as worsening of renal function may warrant change in the dose of a NOAC or change in oral anticoagulant.

Novel oral anticoagulant management issues for the stroke clinician

BACKGROUND

Four nonvitamin K antagonist oral anticoagulants (NOACs) are approved for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF).

AIMS

In this review, we assemble available evidence for the best management of ischemic and hemorrhagic stroke patients in the context of NOAC use.

SUMMARY OF REVIEW

NOACs provide predictable anticoagulation with fixed dosages. The direct thrombin inhibitor dabigatran and direct factor Xa inhibitors apixaban, edoxaban, and rivaroxaban are all noninferior to warfarin for the prevention of ischemic stroke and systemic embolism and are associated with reduced incidence of intracranial hemorrhage. While these agents offer treatment options for NVAF patients, they also present challenges specific to the clinician managing cerebrovascular disease patients.

CONCLUSIONS

We summarize available evidence and current approaches to the initiation, dosing, monitoring and potential reversal of NOACs in stroke patients.