Stroke Prevention in Atrial Fibrillation: Where are We Now?

A Cohort Study on the Safety and Efficacy of Warfarin and Rivaroxaban in Anticoagulant Therapy in Patients with Atrial Fibrillation Study

Objective. To observe the safety and efficacy of warfarin and rivaroxaban in anticoagulation therapy in patients with atrial fibrillation (AF). Methods. A total of 96 patients with AF treated in our hospital from June 2019 to February 2021 were enrolled in this study. According to the different modes of drug administration, the patients were divided into the warfarin group and rivaroxaban group. Demographic and clinical data such as age, body weight, and previous drug use were collected. The blood routine, liver and kidney function, blood coagulation routine, and cardiac color ultrasound were accessed. The valvular atrial fibrillation and anticoagulant taboos were excluded, and the risk of embolism and bleeding was evaluated. Among them, 48 patients in the warfarin group were given warfarin once a day, and the international ratio (INR) was used to adjust the dose, and the INR was controlled between 2.0 and 3.0. In contrast, 48 patients in the rivaroxaban group received a fixed dose of rivaroxaban 20 mg or 15 mg once a day. After administration, regular telephone or outpatient follow-up was given once a month, to monitor patients’ drug compliance and ask if there was bleeding, and to detect blood routine, urine routine, fecal routine+occult blood, and liver and kidney function. In addition, at the beginning of 3, 6, and 12 months of follow-up, each patient was given cardiac color Doppler ultrasound, peripheral vascular color ultrasound, and brain CT to determine whether there were mural thrombosis, stroke, and peripheral arterial thromboembolism. The INR attainment rate, coagulation index, thromboembolism, bleeding, and adverse reactions were compared between the two groups. Results. There was no significant difference in serum Dmurd and NT-proBNP levels between the two groups before treatment and 3, 6, and 9 months after treatment. There was no significant difference in the number of venous embolism, pulmonary embolism, cerebral embolism, and total embolism between the two groups ( $P>0.05$ ). There was no significant difference in the number of mild, moderate, and severe bleeding between the two groups ( $P>0.05$ ), but the total number of bleeding in the rivaroxaban group was lower than that in the warfarin group ( $P<0.05$ ). During the treatment, side effects such as nausea and vomiting, elevated transaminase, glutamyl transpeptidase, and diarrhea occurred between the two groups, and there was no significant difference in the number of adverse reactions between the two groups ( $P>0.05$ ). Conclusion. Compared with warfarin, rivaroxaban anticoagulant therapy has the same advantage in tolerance and prevention of thromboembolism in patients with AF, but rivaroxaban can effectively reduce the risk of bleeding in patients with AF.

A single-arm feasibility cohort study of rivaroxaban in antiphospholipid syndrome

Background

There is uncertainty regarding the safety and effectiveness of direct oral anticoagulant agents in patients with antiphospholipid syndrome (APS). We performed a multicenter feasibility study to examine our ability to identify and obtain consent from eligible APS patients and to obtain 95% adherence with daily rivaroxaban administration, in order to inform and power a larger study. Clinical outcomes of bleeding and thrombosis were also collected.

Methods

APS patients with prior venous thromboembolism (VTE) were recruited over 2 years (Oct 2014-Sept 2016) and followed for ≥ 1 year. Patients were assessed clinically every 3 months and had pill counts performed every 6 months. Numbers of patients fulfilling study criteria, as well as those consenting to participate, were tracked, and percentage adherence based on pill counts was recorded. These data were compared against the feasibility endpoints. Rates of thrombosis and bleeding were calculated. Criterion for feasibility was obtaining consent from 135 of 150 identified APS patients over 2 years.

Results

Ninety-six eligible patients were identified, and 14 declined participation. Eighty-two patients were followed for a mean of 19 months, representing 129.8 patient-years. Average rivaroxaban adherence was 95.0%. During follow-up, there were 4 thromboembolic events (2 cerebrovascular and 2 VTE). There were no episodes of major bleeding.

Conclusions

Adequately powered comparative trials using patient-important outcomes in APS are unlikely to be successful due to inability to recruit sufficient numbers of study subjects. This study does not reveal a higher than expected risk of recurrent thromboembolic disease compared to historical cohorts; however, this is an uncontrolled study in relatively low-risk APS patients.

Trial registration

The study was registered with clinicaltrials.gov, identifier NCT02116036, April 16, 2014.

Stability of High-Quality Warfarin Anticoagulation in a Community-Based Atrial Fibrillation Cohort: The Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study

BACKGROUND

Warfarin reduces ischemic stroke risk in atrial fibrillation (AF) but increases bleeding risk. Novel anticoagulants challenge warfarin as stroke-preventive therapy for AF. They are available at fixed doses but are more costly. Warfarin anticoagulation at a time in therapeutic range (TTR) ≥70% is similarly as effective and safe as novel anticoagulants. It is unclear whether AF patients with TTR ≥70% will remain stably anticoagulated and avoid the need to switch to a novel anticoagulant. We assessed stability of warfarin anticoagulation in AF patients with an initial TTR ≥70%.

METHODS AND RESULTS

Within the community-based Anticoagulation and Risk Factors in AF (ATRIA) cohort followed from 1996 to 2003, we identified 2841 new warfarin users who continued warfarin over 9 months. We excluded months 1 to 3 to achieve a stable dose. For the 987 patients with TTR ≥70% in an initial 6-month period (TTR1; months 4-9), we described the distribution of TTR2 (months 10-15) and assessed multivariable correlates of persistent TTR ≥70%. Of patients with TTR1 ≥70%, 57% persisted with TTR2 ≥70% and 16% deteriorated to TTR2 <50%. Only initial TTR1 ≥90% (adjusted odds ratio 1.47, 95% CI 1.07-2.01) independently predicted TTR2 ≥70%. Heart failure was moderately associated with marked deterioration (TTR2 <50%); adjusted odds ratio 1.45, 95% CI 1.00-2.10.

CONCLUSIONS

Nearly 60% of AF patients with high-quality TTR1 on warfarin maintained TTR ≥70% over the next 6 months. A minority deteriorated to very poor TTR. Patient features did not strongly predict TTR in the second 6-month period. Our analyses support watchful waiting for AF patients with initial high-quality warfarin anticoagulation before considering alternative anticoagulants.

Factors associated with warfarin discontinuation, including bleeding patterns, in atrial fibrillation patients

OBJECTIVE

To determine risk factors for both warfarin discontinuation and bleeding in patients with atrial fibrillation (AF).

METHODS

Data from the MarketScan database (January 2005-June 2008) were retrospectively analyzed for patients ≥18 years old who used warfarin continuously (≥2 prescriptions for 6 months) subsequent to an AF diagnosis. Patients were followed until one of the following endpoints occurred: warfarin discontinuation or end of the 30 month study period (whichever happened first). Recent bleeding was defined as occurring within 90 days before discontinuation. Drug interactions related to bleeding were defined as occurring within 120 days prior to bleeding.

RESULTS

The study included 7971 eligible patients (mean age 67.8 years; 41.2% female). During follow-up, 51.7% of patients discontinued warfarin (P < .001). More patients with recent bleeding (61.8%) discontinued warfarin compared to patients without recent bleeding (51.3%). After adjustment, patients with recent bleeding were 35% more likely to discontinue warfarin compared to those without recent bleeding (relative risk = 1.35; CI: 1.16-1.58). Age >85 years and a history of ≥1 hospitalizations/emergency room visits were associated with an increased likelihood of discontinuation (P < .001). Female gender, daily dosage >5 mg, concomitant use of gastroprotective agents, and CHADS2 scores ≥1 were associated with a decreased likelihood of discontinuation (P < .05).

CONCLUSIONS

Risk factors for warfarin discontinuation include older age, recent bleeding, and a high number of concomitant medications. Risk factors associated with bleeding events are older age, use of a warfarin-potentiating medication, previous bleeding, and higher CHADS2 scores.

Stroke prevention in atrial fibrillation: concepts and controversies

Atrial fibrillation (AF) is the commonest cardiac rhythm disorder worldwide, affecting 1% of the general population. It is estimated that up to 16 million people in the US will suffer from the arrhythmia by 2050. AF is an independent stroke risk factor and associated with more severe strokes. For six decades, warfarin has been the only truly effective therapy to protect against stroke for patients with atrial fibrillation. Despite the proven worth of warfarin, its limitations have seen reluctance amongst physicians and patients to utilise this efficacious agent. This has meant that substantial numbers of patients are either unprotected against stroke or suboptimally protected with antiplatelet therapy.

Contemporary well-validated stroke risk factor schemes (CHA₂DS₂-VASc) now permit rapid but comprehensive evaluation of a patient’s risk for thromboembolism, allowing better identification of low-risk patients who do not require antithrombotic therapy, and whilst for those with ≥1 stroke risk factors require formal oral anticoagulation. Aspirin has been proven to be inferior to anticoagulation, and is not free of bleeding risk. We also have simple scores to easily evaluate a patient’s risk of haemorrhage (e.g. HAS-BLED).

The emergence of new oral anticoagulants should further improve stroke prevention in AF, and they successfully negotiate many of the hurdles to oral anticoagulation generated by warfarin’s limitations. Monitoring, reversal, and perioperative management are areas which require further investigation to enhance our ability to safely and effectively utilise the new agents.

New oral anticoagulants in elderly patients with atrial fibrillation

The prevalence of atrial fibrillation increases with age, augmenting the risk of embolic stroke in elderly individuals. Clinical practice guidelines recommend the long-term use of oral anticoagulation in elderly patients with atrial fibrillation to reduce risk of stroke. Until recently, vitamin K antagonists (eg, warfarin) were the only oral anticoagulants available, but using warfarin in elderly patients can be challenging. Newer oral anticoagulants may offer specific benefits and increased convenience for elderly patients, because they have predictable pharmacologic profiles, a rapid onset of action, a wide therapeutic window, no requirement for routine coagulation monitoring, and fewer and better-defined food and drug interactions compared with warfarin. This review highlights the benefits and challenges of warfarin use in elderly patients with atrial fibrillation and discusses potential efficacy and safety benefits for newer oral agents in these patients. The potential for increased rates of major bleeding in the elderly, particularly those with numerous concomitant medications or renal impairment, also is discussed. Practical considerations for the use of long-term anticoagulation in elderly patients also are discussed.

Thromboprophylaxis of elderly patients with AF in the UK: an analysis using the General Practice Research Database (GPRD) 2000-2009

Objective

To assess use of thromboprophylaxis in UK general practise among patients with atrial fibrillation (AF); to investigate whether elderly patients are less likely to receive anticoagulation therapy than younger patients.

Design

Retrospective cohort study

Setting

UK General Practice Research Database (GPRD)

Patients

Aged ≥60 years with a new diagnosis of AF (2000–2009).

Interventions

None.

Main outcome measures

The main outcome measure was initiation of warfarin in the first year following diagnosis. Patients were categorised by stroke risk (CHADS₂ score) and bleeding risk (HAS-BLED score).

Results

81 381 patients were identified (21% aged 60–69 years, 37% aged 70–79 years, 42% aged 80+ years). Patients aged 80+ years were significantly less likely to be initiated on warfarin than younger patients, adjusted for gender, practice and comorbidities; 32% of patients aged 80+ years received warfarin compared with 57% aged 60–69 years (p<0.0001), and 55% aged 70–79 years (p<0.0001). For all strata of CHADS₂/HASBLED scores, patients aged 80+ years were significantly less likely to be treated with warfarin than younger patients. Logistic regression showed that female sex, low Basal Metabolic Index (BMI), age over 80 years, increasing HAS-BLED score and dementia were independently associated with reduced use of warfarin. Stroke/Transient Ischaemic Attack (TIA), hypertension, heart failure and left ventricular systolic dysfunction were associated with increased use. Patients with HAS-BLED>CHADS₂ were less likely to be initiated on warfarin. Higher CHADS₂ scores were associated with increased anticoagulation use.

Conclusions

Anticoagulation is being under-used in patients with AF aged 80+ years, even after taking into account increased bleeding risk in this age group.