Prognosis of Patients With Ischemic Stroke With Prior Anticoagulant Therapy: Direct Oral Anticoagulants Versus Warfarin.

BACKGROUND: Direct oral anticoagulants (DOACs) have been the drug of choice for preventing ischemic stroke in patients with atrial fibrillation since 2014. In previous studies, the stroke risk while taking warfarin was 2 per 100 patient-years and 1.5% per year while taking DOACs. We hypothesized that even if ischemic stroke occurred during anticoagulation therapy with DOACs, the prognosis was likely to be better than that with warfarin. METHODS AND RESULTS: Data from 2002 to 2019, sourced from a nationwide claims database, were used to identify atrial fibrillation patients using International Classification of Diseases codes. Patients who experienced an ischemic stroke during anticoagulation were categorized by the drugs used (warfarin, dabigatran, apixaban, rivaroxaban, and edoxaban). The primary outcome was mortality within 3 months and 1 year after the ischemic stroke. Among the 9578 patients with ischemic stroke during anticoagulation, 3343 received warfarin, and 6235 received DOACs (965 dabigatran, 2320 apixaban, 1702 rivaroxaban, 1248 edoxaban). The DOACs group demonstrated lower risks of 3-month (adjusted hazard ratio [HR], 0.550, [95% CI, 0.473-0.639]; P<0.0001) and 1-year mortality (adjusted HR, 0.596 [95% CI, 0.536-0.663]; P<0.0001) than the warfarin group. Apixaban and edoxaban within the DOAC group exhibited particularly reduced 1-year mortality risk compared with other DOACs (P<0.0001). CONCLUSIONS: Our study confirmed that DOACs have a better prognosis than warfarin after ischemic stroke. The apixaban and edoxaban groups had a lower risk of death after ischemic stroke than the other DOAC groups.

A pilot study of safety and efficacy comparison of low molecular heparin calcium sequential oral anticoagulants in the treatment of cirrhotic portal vein thrombosis.

BACKGROUND: The objective of this study is to compare and assess the efficacy and safety of low-molecular-weight heparin calcium (LMWH-Ca), followed by either warfarin or rivaroxaban, as treatment options for portal vein thrombosis (PVT) in patients with cirrhosis. METHODS: In this pilot study, cirrhotic (with liver function score of Child-Pugh A) patients diagnosed with PVT who were not on anticoagulant therapy received 2 weeks of subcutaneous injections of LMWH-Ca. They were then randomized to either warfarin (a full course of oral warfarin for 6 months) or rivaroxaban (a full course of oral rivaroxaban for 2 months), with 30 cases in each group. After a treatment period of up to 6 months, a comparative analysis was performed to assess the efficacy and safety of both groups. Volumetric changes in PVT were monitored dynamically using enhanced computed tomography scans before treatment at week 2 and month 6. RESULTS: There were no statistically significant differences in the clinical characteristics of the patients between the two groups. Rivaroxaban treatment reduced PVT median volume from 1.83 cm3 at week 2 to 0.0 cm3 at month 6 and prevented the worsening of PVT after 6 months of treatment with LMWH-Ca (P < 0.001). On the other hand, warfarin treatment increased PVT median volume from 1.95 cm3 at week 2 to 3.78 cm3 at month 6 (P = 0.002). None of the 30 patients in the rivaroxaban group had clinically significant gastrointestinal bleeding, while 2 of the 30 patients (7%) in the warfarin group had gastrointestinal bleeding (P = 0.317). CONCLUSION: Rivaroxaban followed by LMWH-Ca is an effective anticoagulant treatment strategy for PVT in cirrhosis.

Factor Xa Inhibitors Versus Vitamin K Antagonists in Atrial Fibrillation Patients with End-Stage Kidney Disease on Dialysis: A Meta-Analysis.

BACKGROUND: Atrial fibrillation (AF) is prevalent among patients with end-stage kidney disease (ESKD) undergoing dialysis, and both conditions are associated with a heightened risk of cardiovascular diseases. Anticoagulation is essential for preventing thromboembolic complications in these patients. This study aimed to evaluate the effects of factor Xa inhibitors compared to vitamin K antagonists (VKAs) for AF patients on dialysis. METHODS: A comprehensive search of PubMed and Embase databases was conducted to identify relevant studies published up to June 2024. Eligible studies compared factor Xa inhibitors (rivaroxaban, apixaban, edoxaban) with VKAs in AF patients on dialysis, with primary outcomes of stroke or systemic embolism(SSE) and major bleeding. RESULTS: A total of 7 studies (3 randomized controlled trials and 4 observational cohorts) were included. For the RCTs, the use of factor Xa inhibitors was associated with a reduced risk of SSE compared to VKAs (odds ratio [OR] = 0.37, 95% confidence interval [CI]:0.15-0.93). There was no significant difference in the risk of major bleeding events between the two groups (OR = 0.65, 95%CI:0.32-1.33). Observational cohort studies yielded similar results with a decreased risk of SSE (hazard ratio [HR] = 0.74, 95%CI:0.57-0.96) and no significant difference in major bleeding (HR = 0.87, 95%CI:0.62-1.22). No differences in treatment effect between apixaban and rivaroxaban were observed for efficacy (p-interaction = 0.44) and safety (p-interaction = 0.21) outcomes. CONCLUSION: Factor Xa inhibitors, particularly apixaban and rivaroxaban, were associated with a lower risk of SEE without an increase in major bleeding, which might be convenient alternatives to VKAs in managing AF in patients with ESKD on dialysis.

Andexanet alpha versus four-factor prothrombin complex concentrate in DOACs anticoagulation reversal: an updated systematic review and meta-analysis.

BACKGROUND: There is currently a lack of evidence for the comparative effectiveness of Andexanet alpha and four-factor prothrombin complex concentrate (4F-PCC) in anticoagulation reversal of direct oral anticoagulants (DOACs). The primary aim of our systematic review was to verify which drug is more effective in reducing short-term all-cause mortality. The secondary aim was to determine which of the two reverting strategies is less affected by thromboembolic events. METHODS: A systematic review and meta-analysis was performed. RESULTS: Twenty-two studies were analysed in the systematic review and quantitative synthesis. In all-cause short-term mortality, Andexanet alpha showed a risk ratio (RR) of 0.71(95% CI 0.37-1.34) in RCTs and PSMs, compared to 4F-PCC (I2 = 81%). Considering the retrospective studies, the pooled RR resulted in 0.84 (95% CI 0.69-1.01) for the common effects model and 0.82 (95% CI 0.63-1.07) for the random effects model (I2 = 34.2%). Regarding the incidence of thromboembolic events, for RCTs and PSMs, the common and the random effects model exhibited a RR of 1.74 (95% CI 1.09-2.77), and 1.71 (95% CI 1.01-2.89), respectively, for Andexanet alpha compared to 4F-PCC (I2 = 0%). Considering the retrospective studies, the pooled RR resulted in 1.21 (95% CI 0.87-1.69) for the common effects model and 1.18 (95% CI 0.86-1.62) for the random effects model (I2 = 0%). CONCLUSION: Considering a large group of both retrospective and controlled studies, Andexanet alpha did not show a statistically significant advantage over 4F-PCC in terms of mortality. In the analysis of the controlled studies alone, Andexanet alpha is associated with an increased risk of thromboembolic events. CLINICAL TRIAL REGISTRATION: PROSPERO: International prospective register of systematic reviews, 2024, CRD42024548768.

Impact of patient selection in clinical trials: application of ROCKET AF and ARISTOTLE criteria in GARFIELD-AF.

BACKGROUND: The extent to which differences in results from Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) and Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial (ROCKET) atrial fibrillation (AF)-the landmark trials for the approval of apixaban and rivaroxaban, respectively, for non-valvular AF-were influenced by differences in their protocols is debated. The potential influence of selection criteria on trial results was assessed by emulating these trials in data from the Global Anticoagulant Registry in the Field (GARFIELD)-AF registry. METHODS: Vitamin K antagonist (VKA) and non-vitamin K oral antagonist (NOAC) users from GARFIELD-AF were selected according to eligibility for the original ARISTOTLE or ROCKET AF trials. A propensity score overlap weighted Cox model was used to emulate trial randomisation between treatment groups. Adjusted HRs for stroke or systemic embolism (SE) within 2 years of enrolment were calculated for each NOAC versus VKA. RESULTS: Among patients on apixaban, rivaroxaban and VKA, 2570, 3560 and 8005 were eligible for ARISTOTLE, respectively, and 1612, 2005 and 4368, respectively, for ROCKET AF. When selecting for ARISTOTLE criteria, apixaban users had significantly lower stroke/SE risk versus VKA (HR 0.57; 95% CI 0.34 to 0.94) while no reduction was observed with rivaroxaban (HR 0.98; 95% CI 0.68 to 1.40). When selecting for ROCKET AF criteria, safety and efficacy versus VKA were similar across the NOACs. CONCLUSION: Apixaban and rivaroxaban showed similar results versus VKA in high-risk patients selected according to ROCKET AF criteria, whereas differences emerged when selecting for the more inclusive ARISTOTLE criteria. Our results highlight the importance of trial selection criteria in interpreting trial results and underline the problems faced in comparing treatments across rather than within clinical trials.

Apixaban vs Aspirin According to CHA2DS2-VASc Score in Subclinical Atrial Fibrillation: Insights From ARTESiA.

BACKGROUND: ARTESiA (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation) demonstrated that apixaban, compared with aspirin, significantly reduced stroke and systemic embolism (SE) but increased major bleeding in patients with subclinical atrial fibrillation. OBJECTIVES: To help inform decision making, the authors evaluated the efficacy and safety of apixaban according to baseline CHA2DS2-VASc score. METHODS: We performed a subgroup analysis according to baseline CHA2DS2-VASc score and assessed both the relative and absolute differences in stroke/SE and major bleeding. RESULTS: Baseline CHA2DS2-VASc scores were <4 in 1,578 (39.4%) patients, 4 in 1,349 (33.6%), and >4 in 1,085 (27.0%). For patients with CHA2DS2-VASc >4, the rate of stroke was 0.98%/year with apixaban and 2.25%/year with aspirin; compared with aspirin, apixaban prevented 1.28 (95% CI: 0.43-2.12) strokes/SE per 100 patient-years and caused 0.68 (95% CI: -0.23 to 1.57) major bleeds. For CHA2DS2-VASc <4, the stroke/SE rate was 0.85%/year with apixaban and 0.97%/year with aspirin. Apixaban prevented 0.12 (95% CI: -0.38 to 0.62) strokes/SE per 100 patient-years and caused 0.33 (95% CI: -0.27 to 0.92) major bleeds. For patients with CHA2DS2-VASc =4, apixaban prevented 0.32 (95% CI: -0.16 to 0.79) strokes/SE per 100 patient-years and caused 0.28 (95% CI: -0.30 to 0.86) major bleeds. CONCLUSIONS: One in 4 patients in ARTESiA with subclinical atrial fibrillation had a CHA2DS2-VASc score >4 and a stroke/SE risk of 2.2% per year. For these patients, the benefits of treatment with apixaban in preventing stroke/SE are greater than the risks. The opposite is true for patients with CHA2DS2-VASc score <4. A substantial intermediate group (CHA2DS2-VASc =4) exists in which patient preferences will inform treatment decisions. (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Sub-Clinical Atrial Fibrillation; NCT01938248).

Comparison of warfarin, rivaroxaban, and dabigatran for effectiveness and safety in atrial fibrillation patients with different CHA2DS2-VASc scores: a retrospective cohort study.

BACKGROUND: This retrospective cohort study aims to compare the effectiveness and safety of warfarin, rivaroxaban, and dabigatran in atrial fibrillation (AF) patients with different CHA2DS2-VASc scores in northern China. METHODS: A retrospective cohort study was performed to evaluate anticoagulation in AF patients at the second affiliated hospital of Harbin Medical University from September 2018 to August 2019. Patients included in this study (n = 806) received warfarin (n = 300), or rivaroxaban (n = 203), or dabigatran (n = 303). Baseline characteristics and follow-up data including adherence, bleeding events and ischemic stroke (IS) events were collected. RESULTS: Patients receiving rivaroxaban (73.9%) or dabigatran (73.6%) showed better adherence than those receiving warfarin (56.7%). Compared with warfarin-treated patients, dabigatran-treated patients had lower incidence of bleeding events (10.9% vs 19.3%, χ2 = 8.385, P = 0.004) and rivaroxaban-treated patients had lower incidence of major adverse cardiovascular events (7.4% vs 13.7%, χ2 = 4.822, P = 0.028). We classified patients into three groups based on CHA2DS2-VASc score (0-1, 2-3, ≥ 4). In dabigatran intervention, incidence of bleeding events was higher in patients with score 0-1 (20.0%) than those with score 2-3 (7.9%, χ2 = 5.772, P = 0.016) or score ≥ 4 (8.6%, χ2 = 4.682, P = 0.030). Patients with score 0-1 in warfarin or rivaroxaban therapy had a similar but not significant increase of bleeding compared with patients with score 2-3 or score ≥ 4, respectively. During the follow-up, 33 of 806 patients experienced IS and more than half (19, 57.6%) were patients with score ≥ 4. Comparing patients with score 0-1 and 2-3, the latter had an significant reduction of IS in patients prescribed warfarin and non-significant reduction in rivaroxaban and dabigatran therapy. CONCLUSION: Compared with warfarin therapy, patients with different CHA2DS2-VASc scores receiving either rivaroxaban or dabigatran were associated with higher persistence. AF patients with score ≥ 4 were more likely to experience IS events while hemorrhagic tendency preferred patients with low score 0-1.

Direct oral anticoagulant use in hospitalized pediatric patients: Insights from nationwide data.

BACKGROUND: Direct oral anticoagulants (DOACs) have had significant impact on the management of venous thromboembolism (VTE) in adults, but these agents were not approved for use in pediatric patients until 2021. Our objective was to analyze the characteristics of pediatric patients treated with DOACs prior to and following U.S. Food and Drug Administration (FDA) approval for children and evaluate their impact on hospital outcomes. PROCEDURE: We utilized the Epic Cosmos dataset (Cosmos), a de-identified dataset of over 220 million patients, to identify patients aged 1-18 years admitted with a first-occurrence diagnosis of VTE between January 1, 2017 and June 30, 2023. Patients were grouped by anticoagulation received (unfractionated heparin, low molecular weight heparin, and/or DOACs). RESULTS: Among 5138 eligible patients, 18.1% received DOACs as all or part of their anticoagulation treatment, while 81.9% received heparin therapies alone. Patients treated with DOACs were older than patients treated with heparin monotherapy at 17.4 and 13.0 years, respectively. Non-DOAC patients were more likely to have chronic conditions and were less likely to have pulmonary embolism. Patients treated with DOACs demonstrated shorter overall length of stay and duration of intensive care unit (ICU) admission. CONCLUSIONS: DOACs remain infrequently utilized in pediatric patients, especially in those under 13 years old. Initiation on heparin therapy and transition to DOACs remains common, with 80.6% of DOAC patients receiving heparin during their hospitalization. While DOAC monotherapy is not currently endorsed as first-line therapy for DVT or PE in children, it is being used clinically. Further research is needed to clarify the impact of DOAC use on patient adherence, VTE recurrence, and healthcare cost.

Incidence of acute Deep Vein Thrombosis in pediatric and adolescent orthopedic trauma hospitalized patients and effect of rivaroxaban treatment.

OBJECTIVE: Deep vein thrombosis (DVT) provoked by orthopedic trauma is increasing in pediatric hospitalized patients. The purpose of our study is to identify the prevalence of acute DVT in pediatric and adolescent orthopedic trauma hospitalized patients and focus on evaluating the anticoagulation strategies and the clinical outcomes after a confirmed acute DVT. METHODS: Patients (age ≤18 years) with a confirmed acute DVT admitted for orthopedic trauma between September 2017 and December 2023 were included. Patients were classified into the non-anticoagulation (NA), the in-hospital anticoagulation (IHA), and the in-and-out-of-hospital anticoagulation (IOHA) groups based on their anticoagulation regimen. Efficacy outcomes were the venous thromboembolism (VTE) recurrence within 3 months and change in thrombus burden by repeat imaging at 2 weeks after discharge compared with baseline. Safety outcomes were major bleeding (MB) and clinically relevant non-major bleeding (CRNMB) within 3 months. RESULTS: Of the 11,206 pediatric and adolescent orthopedic trauma inpatients, 94(median age,16 [15, 18] years) were diagnosed with acute DVT, with an incidence of 0.84 %, of which 8(8.5 %) received NA, 41(43.6 %) received IHA, and 45(47.9 %) received IOHA. After the diagnosis of DVT, of patients who received anticoagulation, 97.9 % were treated with rivaroxaban as an oral anticoagulant, and 71.7 % received an LMWH course of ≥5 days before starting rivaroxaban therapy. With a median anticoagulation course of 22(8, 37.3) days, the duration in the IOHA was significantly longer than the IHA (37 days vs. 8 days, p = 0.000). No patients experienced recurrent VTE and MB at 3 months, and 1 received IOHA had a CRNMB event (0 % vs. 0 % vs. 2.2 %, p = 1.000). Thrombus resolution was significantly higher in patients who received anticoagulation therapy (IOHA 91.1 % vs. IHA 80.5 % vs. NA 37.5 %, P = 0.002), and thrombus-no relevant change was significantly lower in patients who received the IOHA strategy compared with the other groups (4.4 % vs. 19.5 % vs. 62.5 %, P = 0.000). CONCLUSIONS: A rivaroxaban-predominant IOHA strategy significantly reduced the thrombotic burden without increasing the risk of bleeding for the treatment of DVT in adolescents with orthopedic trauma. Duration of anticoagulation therapy <6 weeks appears appropriate for adolescent orthopedic trauma-related DVT.

Rivaroxaban versus vitamin K antagonist treatment on the progression of coronary calcification: the IRIVASC-trial.

Vitamin K antagonists (VKA) remain the only option of anticoagulation for people with mechanical valve replacement and due to their wider availability and lower acquisition costs, VKA's remain widely used in low- and middle-income countries. It has been suggested that prolonged use of VKAs can increase the development of vascular and valvular calcification, though this effect has not been examined in larger randomized prospective trials. This investigator-initiated multicenter, prospective, randomized, open-label interventional trial randomized patients with baseline coronary or valvular calcification and an indication for prolonged oral anticoagulation therapy to Marcumar or Rivaroxaban. Patients were followed-up through repeat coronary computed tomographies to measure the progression of coronary and valvular calcification for up to 24 months. 192 patients were randomized between 2013 and 2018 to receive either Rivaroxaban or Marcumar and followed for up to 24 months. Coronary calcification significantly increased over time although there was no significant difference in progression between the groups after 12 and 24 months as measured by the Agatston score [360.7 (90.2; 1075.3) vs 380.4 (136.4; 1546.9) p = 0.69], the volume score [295.8 (93.0; 995.3) vs 335.5 (128.7; 1316.9) p = 0.95] and the mass score [58.5 (15.9; 172.0) vs 71.1 (24.8; 257.3) p = 0.5]. Dephosphorylated, uncarboxylated matrix Gla Protein (Dp-ucMGP) significantly decreased in the VKA group [Δ dp-uc MGP - 95.2 (- 554.1; 156.0) vs 231.3 (- 59.7; 388.1) p < 0.001]. There does not appear to be a relevant effect of vitamin K inhibition by the vitamin K antagonist marcumar upon coronary calcification.

Temporal Changes in Long-Term Outcomes of Venous Thromboembolism From the Warfarin Era to the Direct Oral Anticoagulant Era.

BACKGROUND: There have been limited data on the changes in clinical outcomes after the introduction of direct oral anticoagulants (DOACs) for venous thromboembolism (VTE) in real clinical practice. We evaluated the changes in management strategies and long-term outcomes from the warfarin era to the DOAC era. METHODS AND RESULTS: We compared the 2 series of multicenter COMMAND VTE (Contemporary Management and Outcomes in Patients With Venous Thromboembolism) registries in Japan enrolling consecutive patients with acute symptomatic VTE: Registry 1: 3027 patients in the warfarin era (2010-2014) and Registry 2: 5197 patients in the DOAC era (2015-2020). The prevalence of DOAC use increased more in Registry 2 than in the Registry 1 (Registry 1: 2.6% versus Registry 2: 79%, P<0.001). The cumulative 5-year incidence of recurrent VTE was significantly lower in Registry 2 than in Registry 1 (10.5% versus 9.5%, P=0.02), and the risk reduction of recurrent VTE in Registry 2 remained significant even after adjusting the confounders (hazard ratio [HR], 0.78 [95% CI, 0.65-0.93]; P=0.005). The cumulative 5-year incidence of major bleeding was not significantly different between the 2 registries (12.1% versus 13.7%, P=0.26), and the risk of major bleeding between the 2 registries was not significantly different even after adjusting the confounders (HR, 1.04 [95% CI, 0.89-1.21]; P=0.63). CONCLUSIONS: Along with the shift from warfarin to DOACs, there was a lower risk of recurrent VTE in the DOAC era than in the warfarin era, whereas there was no apparent change in the risk of major bleeding, which might still be an unmet need even in the DOAC era.

In device-detected AF, DOACs vs. aspirin or placebo reduce ischemic stroke and increase major bleeding.

SOURCE CITATION: McIntyre WF, Benz AP, Becher N, et al. Direct oral anticoagulants for stroke prevention in patients with device-detected atrial fibrillation: a study-level meta-analysis of the NOAH-AFNET 6 and ARTESiA trials. Circulation. 2024;149:981-988. 37952187.

Apixaban-Induced Hemopericardium in a Post-TAVR Patient: A Case Report Highlighting Diagnostic and Management Challenges.

BACKGROUND Despite having many benefits, frequently-used medications may still have potential risks and can cause harm. Hemopericardium is a lethal pathology with a high risk of mortality and a lower differential diagnosis consideration. When adding both mentioned elements, their consideration as a differential diagnosis would require a higher threshold. This report presents a 66-year-old man with atrial fibrillation, heart failure, and aortic stenosis status post transcatheter aortic valve replacement (TAVR) 1 year ago with hemopericardium while treated with apixaban. CASE REPORT We present the case of a 66-year-old man with multiple medical conditions, including atrial fibrillation, heart failure, and aortic stenosis post-transcatheter aortic valve replacement 1 year before admission, who presented with 2 weeks of dyspnea and lower-limb swelling. Initial assessments revealed atrial fibrillation, elevated brain natriuretic peptide, and a chest X-ray indicating possible left pleural effusion and cardiomegaly. On day 4, an echocardiogram identified a large hemopericardium and tamponade, prompting urgent surgery. A pericardial window was performed, draining 1700 cc of bloody fluid. The postoperative improvement included normalized hemodynamics and echocardiographic findings. Pathology confirmed hemopericardium. The follow-up echocardiogram showed improved cardiac function, and the patient was transferred to the general medical floor. CONCLUSIONS This case sheds light on the uncommon but critical complications associated with direct oral anticoagulant therapy. With only a handful of reported cases, the rarity of this condition underscores the need for heightened awareness among clinicians. The patient's intricate medical history accentuates the challenges in managing anticoagulation in individuals with multiple comorbidities.

Apixaban plasma concentrations before and after catheter ablation for atrial fibrillation.

BACKGROUND: Catheter ablation in patients with atrial fibrillation is associated with a transient increase in thromboembolic risk and adequate anticoagulation is highly important. When patients are anticoagulated with apixaban, monitoring of plasma concentrations of the drug is not routinely performed. This study aimed to assess the influence of clinical patient characteristics, concomitant drug treatment and self-reported adherence on apixaban concentrations, and to describe the intra- and inter-individual variability in apixaban concentrations in this group of patients. Method Apixaban concentrations from 141 patients were measured in plasma one week before ablation and two, six and ten weeks after ablation, employing ultra-high performance liquid chromatography coupled with tandem mass spectrometry. In samples not obtained at trough, apixaban concentrations were adjusted to trough levels. Self-reported adherence was registered by means of the 8-item Morisky Medication Adherence Scale before and after ablation. RESULTS: There were statistically significant, positive correlations between apixaban concentrations and increased age, female sex, lower glomerular filtration rate, higher CHA2DS2-VASc score, use of cytochrome P450 3A4 and/or p-glycoprotein inhibitors, and use of amiodarone. Self-reported adherence was generally high. The mean intra-individual and inter-individual coefficients of variation were 29% and 49%, respectively. CONCLUSION: In patients undergoing catheter ablation for atrial fibrillation, age, sex, renal function, interacting drugs and cerebrovascular risk profile were all associated with altered plasma apixaban concentration. In this group of patients with a generally high self-reported adherence, intra-individual variability was modest, but the inter-individual variability was substantial, and similar to those previously reported in other patient apixaban-treated populations. If a therapeutic concentration range is established, there might be a need for a more flexible approach to apixaban dosing, guided by therapeutic drug monitoring.