Clinical consequences of off-label reduced dosing of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation: a systematic review and meta-analysis

Clinical Features, Management, and Recurrence of Acute Ischemic Stroke Occurring in Patients on Oral Anticoagulant Treatment for Nonvalvular Atrial Fibrillation: A Real-world Retrospective Study

OBJECTIVES

The optimal management of acute ischemic stroke (AIS) in patients with oral anticoagulation (OA) is challenging. Our study aimed to analyze the clinical characteristics and outcome of AIS in patients with OA for nonvalvular atrial fibrillation (NVAF).

METHODS

We retrospectively analyzed data on NVAF patients with AIS on direct oral anticoagulants (DOAC) or vitamin K antagonists (VKA) admitted to our Stroke Unit from 2017 to 2022. Ninety-day modified Rankin Scale (mRS), 90-day, and 12-month stroke recurrences were recorded.

RESULTS

A total of 169 patients (53.2% female, mean age 82.8±6.7 y), 117 (69.2%) on DOAC, and 52 on VKA (30.8%), were enrolled. Mean age, in-hospital mortality, and 90-day mRS ≥4 were significantly higher in VKA patients. 63.4% of VKA patients had subtherapeutic INR, whereas 47.1% of DOAC patients were on low-dose (14.2% off-label). Large vessel occlusion and embolic etiology were more frequent in VKA patients (34.6% vs. 26.4%, P=0.358; 92.3% vs. 74.3%, P=0.007, respectively), whereas lacunar strokes were more frequent in DOAC patients (19.8% vs. 12.2%, P=0.366). Among patients on VKA before AIS 86.4% were switched to DOAC, whereas a DOAC-to-VKA and a DOAC-to-DOAC switch were done in 25.4% and 11.7%, respectively. Stroke recurrence occurred in 6.4% of patients at 90 days and 10.7% at 12 months. Anticoagulant switching was not associated with stroke recurrences.

CONCLUSIONS

In our study, nonembolic etiology was more frequent in DOAC patients and anticoagulant switching did not reduce the risk of stroke recurrence. Prospective multicentric studies are warranted.

Comparative Effectiveness and Safety of Off-Label Underdosed Direct Oral Anticoagulants in Asian Patients with Atrial Fibrillation: A Systematic Review and Meta-analysis

INTRODUCTION

Off-label underdosed direct oral anticoagulants (DOACs) are commonly utilised in Asian patients with atrial fibrillation (AF) since they are prone to bleeding with OACs. However, the efficacy and safety of off-label underdosing DOACs are controversial. This study aimed to compare the effectiveness and safety of off-label underdosed DOACs in Asian patients with AF.

METHODS

PubMed, Embase, Cochrane library, and ClinicalTrials.gov were searched from 2010 to July 5, 2024, for randomised controlled trials or observational studies that compared off-label DOACs and on-label/warfarin in Asian patients with AF. The primary outcomes included ischaemic stroke or systemic embolism (ISSE) and major bleeding (MB), while secondary outcomes included all-cause death, gastrointestinal bleeding (GIB), intracranial haemorrhage (ICH), and myocardial infarction (MI). Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled using random-effects models.

RESULTS

Twenty observational studies were included. Seventeen studies compared off-label underdosed DOACs versus on-label DOACs, whereas five studies compared off-label underdosed DOACs versus warfarin. Off-label underdosed DOACs were associated with higher risk of ISSE (pooled HR [pHR] = 1.17; 95% CI: 1.00-1.38, p = 0.048) and ICH (pHR = 1.27; 95% CI: 1.06-1.52, p = 0.010) versus on-label. Subgroup analysis demonstrated increased ISSE risk with off-label underdosed rivaroxaban compared to on-label (pHR = 1.49; 95% CI: 1.07-2.08). Compared to warfarin, off-label underdosed DOACs were associated with decreased risk of MB (pHR = 0.46; 95% CI: 0.32-0.65, p < 0.001), GIB (pHR = 0.52; 95% CI: 0.29-0.93, p = 0.028), ICH (pHR = 0.60; 95% CI: 0.42-0.86, p = 0.005), and all-cause death (pHR = 0.70; 95% CI: 0.56-0.87, p = 0.001), while illustrating similar ISSE risk.

CONCLUSIONS

Off-label underdosed DOACs, particularly rivaroxaban, was associated with increased ISSE risk but did not decrease bleeding compared to on-label. Adherence to appropriate DOAC doses should be emphasised to achieve the best clinical outcomes for Asian patients with AF.

Acute Ischaemic Stroke in Patients Treated with Direct Oral Anticoagulants: Potential Causes, Clinical Characteristics, and Short-Term Outcomes

Introduction

Direct oral anticoagulants (DOAC) are the first-line treatment for primary and secondary acute ischaemic stroke (AIS) prevention in patients with nonvalvular atrial fibrillation (NVAF), but a significant percentage of patients develop AIS despite being treated with DOAC. As the number of DOAC-treated patients is growing, so is the number of patients with AIS on DOAC. The aim of the study was to assess the incidence of AIS with prestroke DOAC treatment among patients hospitalised in the University Hospital in Kraków, to analyse the clinical characteristics of AIS occurring in patients on DOAC, and to identify potential causes of treatment ineffectiveness in this group.

Materials and Methods

In the study, we included all patients hospitalised in the Department of Neurology of the University Hospital in Kraków within one year (July 2022 to June 2023) with the diagnosis of AIS. The group was divided into two subgroups of patients with and without prestroke DOAC treatment. Based on medical files, we retrospectively analysed the profile of cardiovascular risk factors, stroke severity (assessed with National Institutes of Health Stroke Scale, NIHSS), use of causative stroke treatment and short-term outcomes (defined as NIHSS score, modified Rankin scale (mRS) score at discharge, in-hospital mortality, and secondary intracerebral haemorrhage among patients treated with mechanical thrombectomy, MT). Within the DOAC-treated subgroup, we looked for potential causes of AIS occurring despite DOAC treatment (valvular AF, poor adherence to treatment, underdosing, other prothrombotic conditions, aetiology of stroke other than thromboembolic, and drug-drug interactions).

Results

In the study, we included 768 AIS patients. 109 (14.2%) had a history of prestroke DOAC treatment. A potential cause of DOAC treatment failure was identified in the majority of them (n = 63, 57.8%). Patients with prestroke DOAC treatment had worse functional condition before stroke and higher stroke severity on admission but similar short-term outcomes and similar short-term effects of treatment with MT. DOAC (+) and DOAC (-) patients had different profiles of cardiovascular risk factors and different factors associated with short-term outcome. Conclusions and Clinical Implications. A potential cause of AIS occurring in DOAC-treated patients can be identified in most cases and in many of them prevented.