How effective are dose-adjusted warfarin and aspirin for the prevention of stroke in patients with chronic atrial fibrillation?

Dry Needling and Antithrombotic Drugs

Many clinicians increasingly use dry needling in clinical practice. However, whether patients' intake of antithrombotic drugs should be considered as a contraindication for dry needling has not been investigated to date. As far as we know, there are no publications in analyzing the intake of antiplatelet or anticoagulant agents in the context of dry needling techniques. A thorough analysis of existing medications and how they may impact various needling approaches may contribute to improved evidence-informed clinical practice. The primary purpose of this paper is to review the current knowledge of antithrombotic therapy in the context of dry needling. In addition, reviewing guidelines of other needling approaches, such as electromyography, acupuncture, botulinum toxin infiltration, and neck ultrasound-guided fine-needle aspiration biopsy, may provide specific insights relevant for dry needling. Based on published data, taking antithrombotic medication should not be considered an absolute contraindication for dry needling techniques. As long as specific dry needling and individual risks are properly considered, it does not change the risk and safety profile of dry needling. Under specific circumstances, the use of ultrasound guidance is recommended when available.

Outcomes Associated With Oral Anticoagulants Plus Antiplatelets in Patients With Newly Diagnosed Atrial Fibrillation

IMPORTANCE

Patients with nonvalvular atrial fibrillation at risk of stroke should receive oral anticoagulants (OAC). However, approximately 1 in 8 patients in the Global Anticoagulant Registry in the Field (GARFIELD-AF) registry are treated with antiplatelet (AP) drugs in addition to OAC, with or without documented vascular disease or other indications for AP therapy.

OBJECTIVE

To investigate baseline characteristics and outcomes of patients who were prescribed OAC plus AP therapy vs OAC alone.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of the GARFIELD-AF registry, an international, multicenter, observational study of adults aged 18 years and older with recently diagnosed nonvalvular atrial fibrillation and at least 1 risk factor for stroke enrolled between March 2010 and August 2016. Data were extracted for analysis in October 2017 and analyzed from April 2018 to June 2019.

EXPOSURE

Participants received either OAC plus AP or OAC alone.

MAIN OUTCOMES AND MEASURES

Clinical outcomes were measured over 3 and 12 months. Outcomes were adjusted for 40 covariates, including baseline conditions and medications.

RESULTS

A total of 24 436 patients (13 438 [55.0%] male; median [interquartile range] age, 71 [64-78] years) were analyzed. Among eligible patients, those receiving OAC plus AP therapy had a greater prevalence of cardiovascular indications for AP, including acute coronary syndromes (22.0% vs 4.3%), coronary artery disease (39.1% vs 9.8%), and carotid occlusive disease (4.8% vs 2.0%). Over 1 year, patients treated with OAC plus AP had significantly higher incidence rates of stroke (adjusted hazard ratio [aHR], 1.49; 95% CI, 1.01-2.20) and any bleeding event (aHR, 1.41; 95% CI, 1.17-1.70) than those treated with OAC alone. These patients did not show evidence of reduced all-cause mortality (aHR, 1.22; 95% CI, 0.98-1.51). Risk of acute coronary syndrome was not reduced in patients taking OAC plus AP compared with OAC alone (aHR, 1.16; 95% CI, 0.70-1.94). Patients treated with OAC plus AP also had higher rates of all clinical outcomes than those treated with OAC alone over the short term (3 months).

CONCLUSIONS AND RELEVANCE

This study challenges the practice of coprescribing OAC plus AP unless there is a clear indication for adding AP to OAC therapy in newly diagnosed atrial fibrillation.

Risks of thromboembolism and bleeding with thromboprophylaxis in patients with atrial fibrillation: A net clinical benefit analysis using a ‘real world’ nationwide cohort study

It was the aim of this study to determine the efficacy and safety of vitamin K antagonists (VKAs) and acetylsalicylic acid (ASA) in patients with non-valvular atrial fibrillation (AF), with separate analyses according to predicted thromboembolic and bleeding risk. By individual levellinkage of nationwide registries, we identified all patients discharged with non-valvular AF in Denmark (n=132,372). For every patient, the risk of stroke and bleeding was calculated by CHADS2, CHA2DS2-VASc, and HAS-BLED. During follow-up, treatment with VKA and ASA was determined time-dependently. VKA consistently lowered the risk of thromboembolism compared to ASA and no treatment; the combination of VKA+ASA did not yield any additional benefit. In patients at high thromboembolic risk, hazard ratios (95% confidence interval) for thromboembolism were: 1.81 (1.73–1.90), 1.14 (1.06–1.23), and 1.86 (1.78–1.95) for ASA, VKA+ASA, and no treatment, respectively, compared to VKA. The risk of bleeding was increased with VKA, ASA, and VKA+ASA compared to no treatment, the hazard ratios were: 1.0 (VKA; reference), 0.93 (ASA; 0.89–0.97), 1.64 (VKA+ASA; 1.55–1.74), and 0.84 (no treatment; 0.81–0.88), respectively. There was a neutral or positive net clinical benefit (ischaemic stroke vs. intracranial haemorrhage) with VKA alone in patients with a CHADS2 score of ≥ 0, and CHA2DS2-VASc score of ≥ 1. This large cohort study confirms the efficacy of VKA and no effect of ASA treatment on the risk of stroke/thromboembolism. Also, the risk of bleeding was increased with both VKA and ASA treatment, but the net clinical benefit was clearly positive, in favour of VKA in patients with increased risk of stroke/thromboembolism.

Cost-effectiveness of dabigatran etexilate for the prevention of stroke and systemic embolism in atrial fibrillation: A Canadian payer perspective

Oral dabigatran etexilate is indicated for the prevention of stroke and systemic embolism in patients with atrial fibrillation (AF) in whom anticoagulation is appropriate. Based on the RE-LY study we investigated the cost-effectiveness of Health Canada approved dabigatran etexilate dosing (150 mg bid for patients <80 years, 110 mg bid for patients ≥80 years) versus warfarin and “real-world” prescribing (i.e. warfarin, aspirin, or no treatment in a cohort of warfarin-eligible patients) from a Canadian payer perspective. A Markov model simulated AF patients at moderate to high risk of stroke while tracking clinical events [primary and recurrent ischaemic strokes, systemic embolism, transient ischaemic attack, haemorrhage (intracranial, extracranial, and minor), acute myocardial infarction and death] and resulting functional disability. Acute event costs and resulting long-term follow-up costs incurred by disabled stroke survivors were based on a Canadian prospective study, published literature, and national statistics. Clinical events, summarized as events per 100 patient-years, quality-adjusted life years (QALYs), total costs, and incremental cost effectiveness ratios (ICER) were calculated. Over a lifetime, dabigatran etexilate treated patients experienced fewer intracranial haemorrhages (0.49 dabigatran etexilate vs. 1.13 warfarin vs. 1.05 “real-world” prescribing) and fewer ischaemic strokes (4.40 dabigatran etexilate vs. 4.66 warfarin vs. 5.16 “real-world” prescribing) per 100 patient-years. The ICER of dabigatran etexilate was $10,440/QALY versus warfarin and $3,962/QALY versus “real-world” prescribing. This study demonstrates that dabigatran etexilate is a highly cost-effective alternative to current care for the prevention of stroke and systemic embolism among Canadian AF patients.

Validation of the CHADS2 clinical prediction rule to predict ischaemic stroke

The CHADS2 predicts annual risk of ischaemic stroke in non-valvular atrial fibrillation. This systematic review and meta-analysis aims to determine the predictive value of CHADS2. The literature was systematically searched from 2001 to October 2010. Data was pooled and analysed using discrimination and calibration statistical measures, using a random effects model. Eight data sets (n=2815) were included. The diagnostic accuracy suggested a cut-point of ≥1 has higher sensitivity (92%) than specificity (12%) and a cut-point of ≥4 has higher specificity (96%) than sensitivity (33%). Lower summary estimates were observed for cut-points ≥2 (sensitivity 79%, specificity 42%) and ≥3 (specificity 77%, sensitivity 50%). There was insufficient data to analyse cut-points ≥5 or ≥6. Moderate pooled c statistic values were identified for the classic (0.63, 95% CI 0.52–0.75) and revised (0.60, 95% CI 0.43–0.72) view of stratification of the CHADS2 . Calibration analysis in-dicated no significant difference between the predicted and observed strokes across the three risk strata for the classic or revised view. All results were associated with high heterogeneity, and conclusions should be made cautiously. In conclusion, the pooled c statistic and calibration analysis suggests minimal clinical utility of both the classic and revised view of the CHADS2 in predicting ischaemic stroke across all risk strata. Due to high heterogeneity across studies and low event rates across all risk strata, the results should be interpreted cautiously. Further validation of CHADS2 should perhaps be undertaken, given the methodological differences between many of the available validation studies and the original CHADS2 derivation study.

Risks of stroke and mortality associated with suboptimal anticoagulation in atrial fibrillation patients

Atrial fibrillation (AF) carries an increased risk of ischaemic stroke, and oral anticoagulation with warfarin can reduce this risk. The objective of this study was to evaluate the association between time in therapeutic International Normalised Ratio (INR) range when receiving warfarin and the risk of stroke and mortality. The study cohort included AF patients aged 40 years and older included in the UK General Practice Research Database. For patients treated with warfarin we computed the percentage of follow-up time spent within therapeutic range. Cox regression was used to assess the association between INR and outcomes while controlling for patient demographics, health status and concomitant medication. The study population included 27,458 warfarintreated (with at least 3 INR measurements) and 10,449 patients not treated with antithrombotic therapy. Overall the warfarin users spent 63% of their time within therapeutic range (TTR). This percentage did not vary substantially by age, sex and CHA2DS2-VASc score. Patients who spent at least 70% of time within therapeutic range had a 79% reduced risk of stroke compared to patients with ≤30% of time in range (adjusted relative rate of 0.21; 95% confidence interval 0.18–0.25). Mortality rates were also significantly lower with at least 70% of time spent within therapeutic range. In conclusion, good anticoagulation control was associated with a reduction in the risk of stroke.

Discontinuation/Interruption of Warfarin Therapy in Patients with Nonvalvular Atrial Fibrillation

BACKGROUND

Use of warfarin is standard of care for stroke prevention in patients with atrial fibrillation (AF). However, AF patients experience high rates of warfarin discontinuation/interruption, resulting in increased health risks and health care costs. As such, it is important to study the rates and predictors of warfarin discontinuation/interruption in this population.

OBJECTIVES

To determine (a) rates of warfarin discontinuation and interruption and (b) demographic, clinical, and health care-related factors associated with discontinuation and interruption in patients with nonvalvular AF (NVAF) in the usual clinical practice settings in the United States.

METHODS

This retrospective cohort study used the MarketScan Database and included patients (aged ≥ 18 years) with NVAF who were initiated on warfarin. The study period was January 1, 2008, to June 30, 2012. To be included, patients were required to have at least 2 claims with AF diagnosis separated by ≥ 30 days and ≤ 12 months and at least 1 outpatient claim. Warfarin initiation had to occur within 30 days of the AF diagnosis. Patients also had to have continuous enrollment in prescription drug plans from 6 months prior to warfarin use to at least 12 months after warfarin initiation. Patients were followed for 1 year after warfarin initiation. Persistence was defined as warfarin therapy without a gap ≥ 45 days between the end date of the former prescription and the start date of the current prescription or with international normalized ratio (INR) monitoring at least every 42 days. Interruption was defined as a gap in warfarin therapy ≥ 45 days and ≤ 90 days between the end date of the former prescription and the start date of the current prescription and without INR monitoring at least every 42 days. Discontinuation was defined as greater than 90 days without warfarin therapy between the end date of the former prescription and the start date of the current prescription and without INR monitoring at least every 42 days. Chi-square tests were used to analyze categorical variables, and independent samples t-tests were used for continuous variables. Cox proportional hazards regression model was performed to determine factors associated with warfarin discontinuation/interruption, including demographic (e.g., age, gender); clinical (e.g., comorbidities, CHADS2 score); and health care-related (e.g., hospitalizations or emergency room visits) characteristics. Sensitivity analyses were conducted by varying prescription gaps by 7, 14, and 30 days.

RESULTS

A total of 58,593 patients with NVAF were included. The mean age was approximately 71 years (SD = 12.00) and mean CHADS2 score was 1.66 (SD = 1.23). The majority of patients were male (60%). During 12 months after warfarin initiation, 45% of patients were persistent with warfarin; 12% had interruption without discontinuation; and 43% had discontinuation. The risk of warfarin interruption or discontinuation was significantly greater in patients who were younger than 65 years (HR = 1.22; 95% CI = 1.19-1.25), lived in the West (HR = 1.07; 95% CI = 1.03-1.11), had history of anemia (HR = 1.10; 95% CI = 1.06-1.14), had history of bleeding (HR = 1.10; 95% CI = 1.06-1.14), or had history of hospitalization or emergency room visits (HR = 1.11; 95% CI = 1.08-1.13). The significant factors associated with interruption and discontinuation were similar. In the sensitivity analyses, the significant factors associated with discontinuation/interruption were similar across different prescription gaps.

CONCLUSIONS

In the U.S. clinical practice setting, more than 50% of NVAF patients discontinued or interrupted warfarin within 1 year after initiation. Aged less than  65 years, history of anemia, and history of hospitalization/emergency room visits were associated with increased risk of discontinuation/interruption. Given the high prevalence of warfarin discontinuation/interruption, health care providers should take a more active role in understanding and addressing the reasons behind patient discontinuation/interruption.

Lack of Association of Clinical Factors (SAMe-TT2R2) with CYP2C9/VKORC1 Genotype and Anticoagulation Control Quality

Background and Purpose

Advantages of new oral anticoagulations may be greater in atrial fibrillation (AF) patients of poor anticoagulation control with warfarin. The SAMe-TT₂R₂ scoring system, based on clinical variables, was recently developed to aid in identifying these patients. In this study, we investigated the association of this clinical composite score with genetic factors related warfarin dosing and the quality of anticoagulation control.

Methods

Clinical and genetic data were collected from 380 consecutive Korean patients with AF (CHA₂DS₂-VASc score, 3.5±1.8) who were followed for an average of 4 years. We evaluated factors associated with time in therapeutic range (TTR, INR 2-3), including the CYP2C9 and VKORC1 genotypes and the SAMe-TT₂R₂ score (Sex female, Age <60 years, Medical history [>two co-morbidities], Treatment [interacting drugs, e.g., amiodarone], Tobacco use within 2 years [doubled], and Race non-white [doubled]).

Results

The average SAMe-TT₂R₂ score was 3.4±0.9, range 2-7; and 153 patients (40.2%) had SAMe-TT₂R₂ scores ≥4. Time in specific INR ranges varied depending on the VKORC1 genotype but not with the CYP2C9 genotype or the SAMe-TT₂R₂ score. TTR was higher in patients with the VKORC1 1173C>T than in VKORC1 TT (61.7±16% vs. 56.7±17.4%, P=0.031). Multivariate testing showed that VKORC1 genotype but not the SAMe-TT₂R₂ score was significantly associated with labile INRs. There was no correlation between the SAMe-TT₂R₂ scores and pharmacogenetic data.

Conclusions

A genetic factor, but none of the common clinical and demographic factors, as combined in the SAMe-TT₂R₂ score, was associated with the quality of anticoagulation control in Korean patients with AF.

Topical use of antithrombotics: review of literature

While antithrombotics are usually administered intravenously, subcutaneously or orally, there are a number of publications reporting topical application of anticoagulation therapy. This paper aims to review the available literature regarding clinical conditions, the details of the topical antithrombotic treatment, as well as positive or adverse effects in an attempt to ascertain the safety and efficacy of this form of treatment. Published literature was searched to identify publications reporting the use of antithrombotic treatments administered via topical application between 1st January 1990 and 1st January 2013. There were 43 studies reported in 10 different clinical conditions. Majority of the studies were randomized controlled trials (51.2%), prospective studies (18.6%) or case reports (11.6%). The clinical conditions in which topical antithrombotics were administered included: microangiopathy, acute haemorrhoids, periodontitis, dermatitis, burns, ocular conditions and surgery, blunt force impact, scars, as well as clinical conditions associated with superficial venous thrombosis (SVT). The most commonly used topical antithrombotic was heparin (79.1% of studies). The respective dosage of different antithrombotics varied depending on specific clinical conditions. While most studies reported mean improvements or resolution of symptoms/condition in patients, the patient outcomes were variable. This review demonstrates that topical antithrombotic treatment is used according to a wide variety of protocols, with a subsequent variability in patient outcomes. Specific guidelines for the use of topical antithrombotics should be developed to standardize this form of treatment and ensure the best possible outcomes for patients.

Hospitalized patients with atrial fibrillation compared to those included in recent trials on novel oral anticoagulants: a population-based study

BACKGROUND

Nonvalvular atrial fibrillation is associated with a substantial risk of stroke. Novel oral anticoagulants (NOACs) with predictable anticoagulant effect and no need for routine coagulation monitoring have recently shown good results when compared with warfarin in phase III clinical trials.

OBJECTIVE

To describe clinical features and pharmacological treatments of a population-based cohort of patients with nonvalvular atrial fibrillation and ascertain whether they are comparable with those included in the three main phase III clinical trials on NOACs.

RESULTS

Of the 2,862,264 subjects considered for this study 13,360 patients (0.47%) were recently discharged from the hospital with a diagnosis of nonvalvular atrial fibrillation. Mean age was 76.3 (SD 10.7), 49.8% were men and 64.6% were ≥75 years of age. 50% of patients were treated with warfarin and 44.1% with antiplatelet agents. The proportion of patients on antiplatelet therapy increased with age up to a rate of 54.3% in subjects ≥85 years. 92.9% of the studied cohort was on polypharmacy (mean 8 drugs/patient). Around 20% of the entire cohort was treated with amiodarone, a drug potentially interfering with NOACs, and 3.6% from a subgroup analysis had renal failure, which is an exclusion criterion in trials on NOACs.

CONCLUSION

In patients recently discharged from the hospital with the diagnosis of nonvalvular AF, warfarin use decreases and aspirin treatment increases with patients' age. These patients are older, more frequently female, and on multiple medications. The benefit of NOACs in these subjects needs to be confirmed in phase IV clinical studies.

The patterns of anticoagulation control and the risk of stroke, bleeding and mortality in patients with non-valvular atrial fibrillation

BACKGROUND

Anticoagulation control is often summarized using the percentage of time spent in a therapeutic range (TTR). This method does not describe the timing and severity of fluctuations in the International Normalised Ratio (INR).

OBJECTIVE

To evaluate whether the TTR method can be improved by considering the patterns of INR over time.

METHODS

The cohort included adults aged 40+ years with atrial fibrillation (AF) and laboratory records of INR as recorded in the UK Clinical Practice Research Datalink. Statistical clustering techniques based on simple INR measures were used to describe the patterns of INR. Nested case-control studies calculated the odds ratios (ORs) for the risk of stroke, bleeding and mortality with TTR and different INR patterns. It was also evaluated whether cluster analyses improved the prediction of outcomes over TTR.

RESULTS

A number of 27 381 patients were studied with a mean age of 73 years. The OR for mortality was 3.76 (95% confidence interval [CI] 3.03-4.68) in patients with < 30% TTR compared with patients with 100% TTR. INR patterns were found to be best described by six different clusters. The cluster with the most unstable pattern was associated with the largest risk of mortality (OR 10.7, 95% CI 8.27-13.85) and stroke (OR 3.42, 95% CI 2.08-5.63). INR measures that predicted death independent of the TTR-included absolute difference between two subsequent INR measurements and change relative to the mean over time.

CONCLUSION

Cluster analysis of INR patterns improved the prediction of clinical outcomes over TTR and may help to identify warfarin users who need additional anticoagulation monitoring.

Home-monitoring of oral anticoagulation vs. dabigatran. An indirect comparison

Oral anticoagulation with vitamin k antagonists (VKAs) requires regular testing and dose adjustment. Home-monitoring (self-testing or self-management) is more effective than usual management. Dabigatran, does not require dose-adjustment and appears to be more effective at reducing the risk of stroke with similar risks of bleeding in patients with atrial fibrillation (AF). Dabigatran, however, has not been compared to the home-monitoring. It was the objective to evaluate the efficacy of dabigatran compared with home-monitoring of oral anticoagulation with VKAs. Randomised controlled trials (RCTs) comparing usual management of oral anticoagulation with home-monitoring, dabigatran with usual management, and RCTs comparing dabigatran with home-monitoring and including patient-important outcomes (thromboembolic events, death and major bleeding) were eligible. For our direct comparison we calculated pooled relative risks (RRs) using the Mantzel-Haenzel random effect model. For the indirect comparison we estimated lnRRs and back transformed to RR. We evaluated the quality of the evidence with the GRADE system. Dabigatran, compared with warfarin, was associated with lower rates of stroke or thromboembolism and systemic embolism but similar rates of major haemorrhage and death. Dabigatran 150 mg also increased non-significantly the rate of myocardial infarction. The quality of the evidence was high. Our indirect comparison of home-monitoring of oral anticoagulation versus dabigatran showed no convincing differences in the risk of thromboembolism, death or major bleeding. The estimates for self-management vs. dabigatran showed stronger but still non-significant trends. The quality of the evidence was low. In conclusion, the indirect comparison of home monitoring of oral anticoagulation with dabigatran suggests that the treatments have similar impact on thrombosis, bleeding and death. However, the confidence in the estimate of effect is low to very low. Our analyses contrast with the available comparison of dabigatran with conventional warfarin monitoring.

Stroke and bleeding in atrial fibrillation with chronic kidney disease

BACKGROUND

Both atrial fibrillation and chronic kidney disease increase the risk of stroke and systemic thromboembolism. However, these risks, and the effects of antithrombotic treatment, have not been thoroughly investigated in patients with both conditions.

METHODS

Using Danish national registries, we identified all patients discharged from the hospital with a diagnosis of nonvalvular atrial fibrillation between 1997 and 2008. The risk of stroke or systemic thromboembolism and bleeding associated with non-end-stage chronic kidney disease and with end-stage chronic kidney disease (i.e., disease requiring renal-replacement therapy) was estimated with the use of time-dependent Cox regression analyses. In addition, the effects of treatment with warfarin, aspirin, or both in patients with chronic kidney disease were compared with the effects in patients with no renal disease.

RESULTS

Of 132,372 patients included in the analysis, 3587 (2.7%) had non-end-stage chronic kidney disease and 901 (0.7%) required renal-replacement therapy at the time of inclusion. As compared with patients who did not have renal disease, patients with non-end-stage chronic kidney disease had an increased risk of stroke or systemic thromboembolism (hazard ratio, 1.49; 95% confidence interval [CI], 1.38 to 1.59; P<0.001), as did those requiring renal-replacement therapy (hazard ratio, 1.83; 95% CI, 1.57 to 2.14; P<0.001); this risk was significantly decreased for both groups of patients with warfarin but not with aspirin. The risk of bleeding was also increased among patients who had non-end-stage chronic kidney disease or required renal-replacement therapy and was further increased with warfarin, aspirin, or both.

CONCLUSIONS

Chronic kidney disease was associated with an increased risk of stroke or systemic thromboembolism and bleeding among patients with atrial fibrillation. Warfarin treatment was associated with a decreased risk of stroke or systemic thromboembolism among patients with chronic kidney disease, whereas warfarin and aspirin were associated with an increased risk of bleeding. (Funded by the Lundbeck Foundation.).

A net clinical benefit analysis of warfarin and aspirin on stroke in patients with atrial fibrillation: a nested case-control study

Background

As the management of patients treated with anticoagulants and antiplatelet drugs entails balancing coagulation levels, we evaluated the net clinical benefit of warfarin and aspirin on stroke in a large cohort of patients with atrial fibrillation (AF).

Methods

A population-based cohort study of all patients at least 18 years of age with a first-ever diagnosis of chronic AF during the period 1993–2008 was conducted within the United Kingdom General Practice Research Database. A nested case–control analysis was conducted to estimate the risk of ischemic stroke and intracranial hemorrhage associated with the use of warfarin and aspirin. Cases were matched up to 10 controls on age, sex, and date of cohort entry. The adjusted net clinical benefit of warfarin and aspirin (expressed as the number of strokes prevented per 100 persons per year) was calculated by subtracting the ischemic stroke rate (prevented by therapy) from the intracranial hemorrhage (ICH) rate (increased by therapy).

Results

The cohort included 70,766 patients newly-diagnosed with chronic AF, of whom 5519 experienced an ischemic stroke and 689 an ICH during follow-up. The adjusted net clinical benefit of warfarin was 0.59 (95% CI: 0.45, 0.73). However, the benefit was not seen for patients below (0.08, 95%: -0.38, 0.54) and above (−0.49, 95% CI: -1.13, 0.15) therapeutic range. The net clinical benefit of warfarin, apparent after 3 months of continuous use, increased as a function of CHADS₂ score. The net clinical benefit was not significant with aspirin (−0.07, 95% CI: -0.22, 0.08), though it was seen in certain subgroups.

Conclusions

Warfarin provides a net clinical benefit in patients with atrial fibrillation, which is maintained with longer duration of use, particularly when used within therapeutic range. A similar net effect is not as clear with aspirin.

Atrial fibrillation and vascular disease--a bad combination

This article provides an overview of (i) the risk of stroke associated with vascular disease (acute coronary syndromes and peripheral artery disease) in patients with atrial fibrillation, (ii) the frequent coexistence of vascular disease in patients with atrial fibrillation and, (iii) the cardiovascular risk associated with the coexisting of the two diseases. The literature on this topic is relatively sparse, and we discuss results from both clinical trials and observational studies. There is a clear indication of an increased stroke risk associated with vascular disease in patients with atrial fibrillation. Indeed, patients with atrial fibrillation often had coexisting vascular disease (around 18%), and the combination of the two diseases substantially increases the risk of future cardiovascular events. The increased risk associated with peripheral artery disease in atrial fibrillation is even more pronounced. Patients with atrial fibrillation and stable vascular disease should be treated with oral anticoagulation only, although when these patients present with acute coronary syndrome and/or undergo coronary stenting, concomitant treatment with antiplatelet drugs is indicated. To guide antithrombotic management in patients with atrial fibrillation, several stroke and bleeding risk prediction schemes have been developed.

Stroke in atrial fibrillation: epidemiology and thromboprophylaxis

Atrial fibrillation (AF) is the commonest sustained cardiac rhythm disorder, which is associated with a substantial risk of mortality and morbidity arising from stroke and thromboembolism. Extensive epidemiological evidence and robust data from clinical trials have shown that stroke and thromboembolism in AF can be prevented by oral anticoagulation (OAC). Despite this evidence and guidelines, appropriate thromboprophylaxis is still suboptimal, and this is partly due to the only OAC agent being available is the vitamin K antagonist class of drugs (e.g. warfarin) that has many limitations and disadvantages. With the availability of new OAC agents that avoid the disutility of the vitamin K antagonists, it is hoped that greater use of OAC would allow more effective thromboprophylaxis and have a great impact on preventing strokes related to AF. Additionally, stroke risk assessments need to evolve such that they are better at identifying the 'truly low risk' subjects who do not need antithrombotic therapy, whilst all other patients with ≥ 1 stroke risk factors can be considered for OAC. The availability of comprehensive stroke and bleeding risk assessments would enable us to make informed decisions in everyday clinical practice. The aim of the review article is to provide a state-of-the-art overview of the clinical epidemiology of stroke in AF, stroke (and bleeding) risk assessments and the current provision of thromboprophylaxis for patients with AF.

[Should dabigatran or vitamin K antagonists be used in prevention of stroke in patients with atrial fibrillation?]

Patients with atrial fibrillation (AF) at risk of stroke are not always anticoagulated with vitamin K antagonists (VKA) despite lack of contraindication. Dabigatran, an oral direct thrombin inhibitor, is a new option with proven safety and effectiveness in these patients. The advantages of dabigatran are its more predictable response, obviating coagulation monitoring and possible lower frequency of bleedings. Its drawbacks are cost, lack of antidote and long-term data, frequency of dyspepsia and the twice daily dosage.

A comparison of risk stratification schemes for stroke in 79,884 atrial fibrillation patients in general practice

BACKGROUND

Anticoagulation management of patients with atrial fibrillation (AF) should be tailored individually on the basis of ischemic stroke risk. The objective of this study was to compare the predictive ability of 15 published stratification schemes for stroke risk in actual clinical practice in the UK.

METHODS

AF patients aged ≥ 18 years in the General Practice Research Database, which contains computerized medical records, were included. The c-statistic was estimated to determine the predictive ability for stroke for each scheme. Outcomes included stroke, hospitalizations for stroke, and death resulting from stroke (as recorded on death certificates).

RESULTS

The study cohort included 79,844 AF patients followed for an average of 4 years (average of 2.4 years up to the start of warfarin therapy). All risk schemes had modest discriminatory ability in AF patients, with c-statistics for predicting events ranging from 0.55 to 0.69 for strokes recorded by the general practitioner or in hospital, from 0.56 to 0.69 for stroke hospitalizations, and from 0.56 to 0.78 for death resulting from stroke as reported on death certificates. The proportion of patients assigned to individual risk categories varied widely across the schemes, with the proportion categorized as moderate risk ranging from 12.7% (CHA(2) DS(2)-VASc) to 61.5% (modified CHADS(2)). Low-risk subjects were truly low risk (with annual stroke events < 0.5%) with the modified CHADS(2), National Institute for Health and Clinical Excellence and CHA(2) DS(2) -VASc schemes.

CONCLUSION

Current published risk schemes have modest predictive value for stroke. A new scheme (CHA(2) DS(2) -VASc) may discriminate those at truly low risk and minimize classification of subjects as intermediate/moderate risk. This approach would simplify our approach to stroke risk stratification and improve decision-making for thromboprophylaxis in patients with AF.