Comparison of idraparinux with vitamin K antagonists for prevention of thromboembolism in patients with atrial fibrillation: a randomised, open-label, non-inferiority trial

Anticoagulants: From chance discovery to structure-based design

Taking a historical perspective, we review the discovery, pharmacology, and clinical evaluation of the old and new anticoagulants that have been approved for clinical use. The drugs are discussed chronologically, starting in the 1880s, and progressing through to 2024. The innovations in technology used to develop novel anticoagulants came in fits and starts and reflected the advances in science and technology over these decades, whereas the shift from anecdote to evidence-based use of anticoagulants was delayed until the principles of epidemiology and biostatistics were introduced into clinical trial design and to the approval process. Hirudin, heparin, and vitamin K antagonists were discovered by chance, and were used clinically before their mechanism of action was elucidated and before their net clinical benefits were evaluated in randomized clinical trials. Subsequent anticoagulants were designed based on a better understanding of the structure and function of coagulation proteins, including antithrombin, thrombin, and factor Xa, and underwent more rigorous preclinical and clinical evaluation before regulatory approval. By simplifying oral anticoagulation, the direct oral anticoagulants have revolutionized anticoagulation care and have enhanced the uptake of anticoagulation, but bleeding has not been eliminated and there is a need for more effective and convenient anticoagulants for thrombosis triggered by the contact pathway of coagulation. The newly developed factor XIa and XIIa inhibitors have the potential to address these unmet clinical needs and are undergoing clinical evaluation for several indications. SIGNIFICANCE STATEMENT: Anticoagulant therapy is the cornerstone of treatment and prevention of thrombosis, which remains a leading cause of morbidity and mortality worldwide. Elucidation of the structure and function of coagulation enzymes, their cofactors, and inhibitors, coupled with advances in structure-based design led to the discovery of more convenient, safer, and more effective anticoagulants that have revolutionized the management of thrombotic disorders.

Non-Inferiority Trials in Stroke Research: What Are They, and How Should We Interpret Them?

Randomized clinical trials are important in both clinical and academic stroke communities with increasing numbers of new design concepts emerging. One of the "less traditional" designs that have gained increasing interest in the last decade is non-inferiority trials. Whilst the concept might appear straightforward, the design and interpretation of non-inferiority trials can be challenging. In this review, we will use exemplars from clinical trials in the stroke field to provide an overview of the advantages and limitations of non-inferiority trials and how they should be interpreted in stroke research.

Relationship between temporal rhythm-based classification of atrial fibrillation and stroke: real-world vs. clinical trial

Background

The risk of stroke according to clinical classification of atrial fibrillation (AF) remains poorly defined. Here, we assessed the impact of AF type on stroke risk in vitamin K antagonist-treated patients with AF in ‘real-world’ and ‘clinical trial’ cohorts.

Methods

Post-hoc analysis of patient-level data from the Murcia AF Project and AMADEUS trial. Clinical classification of AF was based on contemporary recommendations from international guidelines. Study endpoint was the incidence rate of ischaemic stroke. Stroke risk was determined using CHA₂DS₂-VASc score and CARS. A modified CHA₂DS₂-VAS‘c’ score that applied one additional point for a ‘c’ criterion of continuous AF (i.e. non-paroxysmal AF) was calculated.

Results

We included 5,917 patients: 1,361 (23.0%) real-world and 4,556 (77.0%) clinical trial. Baseline demographics were balanced in the real-world cohort but clinical trial participants with non-pAF (vs. pAF) were older, male-predominant and had more comorbidities. Crude stroke rates were comparable between the groups in real-world patients (IRR 0.72 [95% CI,0.37-1.28], p = 0.259) though clinical trial participants with non-pAF had a significantly higher crude rate of stroke events (IRR 4.66 [95%,CI,2.41-9.48], p < 0.001). Using multivariable analysis, AF type was not independently associated with stroke risk in the real-world (adjusted HR 1.41 [95% CI,0.80-2.50], p = 0.239) and clinical trial (adjusted HR 1.16 [95% CI,0.62-2.20], p = 0.646) cohorts, after accounting for other risk factors. There was no significant improvement in the CHA₂DS₂-VAS‘c’ compared to CHA₂DS₂-VASc score in either cohorts (p > 0.05).

Conclusions

Overall, our results support the need for anticoagulation based on thromboembolic risk profile rather than AF type.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11239-022-02638-0.

Prediction of Residual Stroke Risk in Anticoagulated Patients with Atrial Fibrillation: mCARS

Our ability to evaluate residual stroke risk despite anticoagulation in atrial fibrillation (AF) is currently lacking. The Calculator of Absolute Stroke Risk (CARS) has been proposed to predict 1-year absolute stroke risk in non-anticoagulated patients. We aimed to determine whether a modified CARS (mCARS) may be used to assess the residual stroke risk in anticoagulated AF patients from ‘real-world’ and ‘clinical trial’ cohorts. We studied patient-level data of anticoagulated AF patients from the real-world Murcia AF Project and AMADEUS clinical trial. Individual mCARS were estimated for each patient. None of the patients were treated with non-vitamin K antagonist oral anticoagulants. The predicted residual stroke risk was compared to actual stroke risk. 3503 patients were included (2205 [62.9%] clinical trial and 1298 [37.1%] real-world). There was wide variation of CARS for each category of CHA₂DS₂-VASc score in both cohorts. Average predicted residual stroke risk by mCARS (1.8 ± 1.8%) was identical to actual stroke risk (1.8% [95% CI, 1.3–2.4]) in the clinical trial, and broadly similar in the real-world (2.1 ± 1.9% vs. 2.4% [95% CI, 1.6–3.4]). AUCs of mCARS for prediction of stroke events in the clinical trial and real-world were 0.678 (95% CI, 0.598–0.758) and 0.712 [95% CI, 0.618–0.805], respectively. mCARS was able to refine stroke risk estimation for each point of the CHA₂DS₂-VASc score in both cohorts. Personalised residual 1-year absolute stroke risk in anticoagulated AF patients may be estimated using mCARS, thereby allowing an assessment of the absolute risk reduction of treatment and facilitating a patient-centred approach in the management of AF. Such identification of patients with high residual stroke risk could help target more aggressive interventions and follow-up.

Relationship between Chronic Kidney Disease, Time-in-Therapeutic Range, and Adverse Outcomes in Atrial Fibrillation: A post hoc Analysis from the AMADEUS Trial

BACKGROUND

The benefit of anticoagulation therapy in atrial fibrillation (AF) and chronic kidney disease (CKD) remains controversial. We aimed to evaluate the impact of renal function on the quality of anticoagulation control, and the effects of both these factors on outcomes in AF.

METHODS

Post hoc analysis of the AMADEUS trial. Trial-related outcomes were adjudicated and we studied the composite of first stroke/major bleeding/all-cause mortality, ischaemic stroke, major bleeding, all-cause mortality, and cardiovascular mortality.

RESULTS

We included 2,282 vitamin K antagonist (VKA)-treated patients {n = 787 (34.5%) females; median age 72 (interquartile ranges [IQR] 64-77) years}. Median follow-up was 365 (IQR 189-460) days. There were 1,922 (84.2%) non-CKD and 360 (15.8%) CKD patients. Renal function was inversely correlated with time-in-therapeutic range (r = -0.047, p = 0.025). There was no statistical difference in terms of crude study outcomes based on renal function. Multivariable regression analysis demonstrated that moderate renal failure with estimated glomerular filtration rate of less than 60 mL/min/1.73 m2 (p = 0.032) and percentage of time-in-therapeutic range (p = 0.011) were independent predictors for the composite outcome of stroke, major bleeding, and all-cause mortality.

CONCLUSION

Deteriorated renal function has a small negative impact on the quality of anticoagulation control with VKA which is linked to poor outcomes in AF. However, moderate renal failure itself was an independent risk factor for increased risk of stroke, major bleeding, and all-cause mortality amongst patients with AF.

Clinical Phenotype Classification of Atrial Fibrillation Patients Using Cluster Analysis and Associations with Trial-Adjudicated Outcomes

BACKGROUND AND PURPOSE

Given the great clinical heterogeneity of atrial fibrillation (AF) patients, conventional classification only based on disease subtype or arrhythmia patterns may not adequately characterize this population. We aimed to identify different groups of AF patients who shared common clinical phenotypes using cluster analysis and evaluate the association between identified clusters and clinical outcomes.

METHODS

We performed a hierarchical cluster analysis in AF patients from AMADEUS and BOREALIS trials. The primary outcome was a composite of stroke/thromboembolism (TE), cardiovascular (CV) death, myocardial infarction, and/or all-cause death. Individual components of the primary outcome and major bleeding were also assessed.

RESULTS

We included 3980 AF patients treated with the Vitamin-K Antagonist from the AMADEUS and BOREALIS studies. The analysis identified four clusters in which patients varied significantly among clinical characteristics. Cluster 1 was characterized by patients with low rates of CV risk factors and comorbidities; Cluster 2 was characterized by patients with a high burden of CV risk factors; Cluster 3 consisted of patients with a high burden of CV comorbidities; Cluster 4 was characterized by the highest rates of non-CV comorbidities. After a mean follow-up of 365 (standard deviation 187) days, Cluster 4 had the highest cumulative risk of outcomes. Compared with Cluster 1, Cluster 4 was independently associated with an increased risk for the composite outcome (hazard ratio (HR) 2.43, 95% confidence interval (CI) 1.70-3.46), all-cause death (HR 2.35, 95% CI 1.58-3.49) and major bleeding (HR 2.18, 95% CI 1.19-3.96).

CONCLUSIONS

Cluster analysis identified four different clinically relevant phenotypes of AF patients that had unique clinical characteristics and different outcomes. Cluster analysis highlights the high degree of heterogeneity in patients with AF, suggesting the need for a phenotype-driven approach to comorbidities, which could provide a more holistic approach to management aimed to improve patients' outcomes.

Number needed to treat for net effect of anticoagulation in atrial fibrillation: Real-world vs. clinical-trial evidence

AIMS

The net benefit of oral anticoagulants (OACs) in atrial fibrillation (AF) is poorly understood. We aimed to determine the NNT for net effect (NNT_net ) using calculator of absolute stroke risk (CARS) in anticoagulated patients with AF in real-world and clinical trial cohorts.

METHODS

Post-hoc analysis of patient-level data from the real-world Murcia AF Project and AMADEUS clinical trial. Baseline risk of stroke was determined using CARS. The risk of stroke and major bleeding events with OAC were determined using the number of respective events at 1-year. NNT_net was calculated as a reciprocal of the net effect of absolute risk reduction with OAC (NNT_net  = 1/(absolute risk reduction of stroke[ARR_stroke ] - absolute risk increase of major bleeding[ARI_bleeding ])).

RESULTS

In total, 3511 patients were included (1306 [37.2%] real-world patients and 2205 [62.8%] clinical trial participants). The absolute 1-year stroke risk was similar across both cohorts. In the real-world cohort, OAC was associated with a 4.0% ARR_stroke , 25 NNT_benefit , 1.0% ARI_bleeding , 100 NNT_harm and 34 NNT_net . In the clinical trial cohort, OAC was associated with a 3.8% ARR_stroke , 27 NNT_benefit , 1.6% ARI_bleeding , 63 NNT_harm and 46 NNT_net . In both cohorts, the NNT_net was significantly lower in patients with an excess stroke risk of ≥2% by CARS.

CONCLUSION

Overall, the NNT_net approach in AF incorporates information regarding baseline risk of stroke and major bleeding, and relative effects of OAC with the potential to include multiple additional outcomes and weighting of events based on their perceived effects by individual patients.

Comparative Analysis of Risk Stratification Scores in Atrial Fibrillation

BACKGROUND

Atrial Fibrillation (AF) has become a major global health concern and is associated with an increased risk of poor outcomes. Identifying risk factors in patients with AF can be challenging, given the high burden of comorbidities in these patients. Risk stratification schemes appear to facilitate accurate prediction of outcomes and assist therapeutic management decisions.

OBJECTIVE

To summarize current evidence on risk stratification scores for patients with AF.

RESULTS

Traditional risk models rely heavily on demographics and comorbidities, while newer tools have been gradually focusing on novel biomarkers and diagnostic imaging to facilitate more personalized risk assessment. Several studies have been conducted to compare existing risk schemes and identify specific patient populations in which the prognostic ability of each scheme excels. However, current guidelines do not appear to encourage the implementation of risk models in clinical practice, as they have not incorporated new ones in their recommendations for the management of patients with AF for almost a decade.

CONCLUSION

Further work is warranted to analyze new reliable risk stratification schemes and optimally implement them into routine clinical life.

Outcomes in VKA-treated patients with atrial fibrillation and chronic kidney disease: Clinical trials vs 'real-world'

BACKGROUND

Our objectives were to evaluate the risk of adverse events in a 'real-world' vs 'clinical trial' cohort of atrial fibrillation (AF) patients with chronic kidney disease (CKD).

METHODS

We studied patient-level data for vitamin K antagonist-treated AF patients with a creatinine clearance <60 mL/min from the Murcia AF Project and AMADEUS trial. The study end-points were ischaemic stroke, major bleeding, all-cause mortality, myocardial infarction and intracranial haemorrhage.

RESULTS

This study included 1,108 AF patients with CKD. The annual rate of the composite study outcome of ischaemic stroke, major bleeding and all-cause mortality was higher in the real-world (13.4%) vs AMADEUS (6.6%) cohort with an IRR of 2.04 (95% CI,1.34-3.09), P < .001. Individual annual rates of major bleeding, all-cause mortality and non-cardiovascular mortality were significantly greater in the real-world cohort. Similar findings were demonstrated even after multivariable adjustment, with the composite outcome HR of 2.85 (95% CI,1.74-4.66), P < .001. In a propensity score matched cohort, this risk remained significantly higher in the real-world cohort (IRR 2.95 [95% CI,1.03-10.28], P = .027), as did the risk of major bleeding and all-cause mortality.

CONCLUSION

Vitamin K antagonist-treated AF patients with CKD are exposed to significant annual rates of major adverse events including all-cause mortality. This risk may be under-appreciated in the idealised environment of randomised controlled trials.

Effects of Atrial Fibrillation and Chronic Kidney Disease on Major Adverse Cardiovascular Events

Atrial fibrillation (AF) is strongly linked to chronic kidney disease (CKD) and both of these conditions contribute to poor cardiovascular outcomes. We evaluated the impact of renal failure on major adverse cardiovascular events (MACE) in AF, and predictive value of the 2MACE score in this post-hoc analysis of the AMADEUS trial. The primary endpoint was MACE (composite of myocardial infarction, cardiac revascularisation and cardiovascular mortality). Secondary endpoints included the composite of stroke, major bleeding and non-cardiovascular mortality, and each of the specific outcomes separately. Of the 4,554 patients, 1,526 (33.5%) were females and the median age was 71 (IQR 64 to 77) years. There were 3,838 (84.3%) non-CKD and 716 (15.7%) CKD patients. The incidence of cardiovascular and non-cardiovascular mortality were 1.41% and 2.44% per 100 patient-years, respectively. There was no significant difference in crude study endpoints between the groups. Multivariable regression analysis found no association between CKD and MACE (HR 1.03 [95% CI, 0.45 to 2.34]). The c-index of the 2MACE score for MACE was 0.65 (95% CI, 0.59 to 0.71, p <0.001). In the presence of CKD, each additional point of the 2MACE score contributed to a greater risk of MACE (HR 3.17 [95% CI, 1.28 to 7.85] vs 1.48 [95% CI, 1.17 to 1.87] in the non-CKD group). In conclusion, the 2MACE score may be a useful tool for clinical risk stratification of high-risk AF patients with CKD and those at high MACE risk could be targeted for more intensive cardiovascular prevention strategies. The presence of CKD was not found to be independently associated with MACE in AF patients.

Ischemic stroke and non-valvular atrial fibrillation: When to introduce anticoagulant therapy?

About 20 to 30% of ischemic strokes are related to non-valvular atrial fibrillation. This type of situation is particularly at risk for both recurrence of the ischemic event and the hemorrhagic transformation of this stroke. The timing of the introduction or going back to the anticoagulant therapy in these patients remains a difficult issue, with a complex benefit-risk balance that needs to be assessed. Randomized controlled studies are lacking and current recommendations do not allow for clear decision making. The administration of a curative anticoagulant within 72 hours after the event is not recommended in the absence of demonstrated efficacy in preventing recurrence at this stage and because of the risk of intracerebral hemorrhage. This attitude can nevertheless be qualified by a transient accident or ischemic accident of very small size, and in the absence of any other risk factor for intra- or extra-cerebral hemorrhage. From the 4th day, after an appropriate case by case evaluation, the introduction of anticoagulant would be possible within a time which will remain at the appreciation of the medical teams. If the patient's risk of an intracerebral hemorrhage or general bleeding is transiently increased, it will be preferable to wait at least 2 weeks after the stroke. If this risk persists in the long term, the decision of the administration or not of an anticoagulant will have to be made with a multidisciplinary consultation. Vitamin K antagonists or direct oral anticoagulants may be prescribed as first-line therapy for the prevention of recurrence of ischemic stroke in a non-valvular atrial fibrillation patient. The choice will be based on the clinical and biological data of each patient. Direct oral anticoagulants have not shown superiority in the prevention of ischemic recurrence but open up new prospects for earlier treatment if their lesser risk of bleeding is confirmed after further studies.

Clinical outcomes associated with kidney function changes in anticoagulated atrial fibrillation patients: An ancillary analysis from the BOREALIS trial

BACKGROUND

Patients with atrial fibrillation (AF) and chronic kidney disease represent a high-risk group for thromboembolism and bleeding.

AIMS

To explore the relationship between kidney function changes and outcomes of stroke/systemic embolism (SE), major bleeding and all-cause death in anticoagulated AF patients participating in the BOREALIS trial comparing efficacy and safety of once-weekly s.c. idrabiotaparinux to that of warfarin.

METHODS

Changes in kidney function by estimated glomerular filtration rate (eGFR) were calculated using the Chronic Kidney Disease Epidemiology Collaboration equation in 2765 AF patients. Trial adjudicated outcomes were determined.

RESULTS

After a mean follow-up of 394 days, in 94.4% of the included patients kidney function changed ranging from -30 mL/min to 30 mL/min. The incidence of stroke/SE and major bleeding was similar between patients with deteriorated (reduction in eGFR from baseline over follow-up) and preserved kidney function change (increase or no change in eGFR from baseline over follow-up) [stroke/SE: incidence rate (IR): 1.33%/year vs 1.80%/year; hazard ratio (HR) 0.74, 95% confidence interval (CI) 0.41-1.32, P = .30; major bleeding: IR 1.63%/year vs 1.49%/year, HR 1.10, 95% CI 0.61-1.97, P = .76]. On Cox regression analysis, patients with deteriorated kidney function were at higher risk for all-cause death, compared to patients with preserved kidney function (HR: 1.64, 95% CI: 1.02-2.63, P = .04).

CONCLUSION

In the BOREALIS trial, the risk of adjudicated stroke/SE, major bleedings, and all-cause death was not related to mild-moderate follow-up changes in kidney function (±30 mL/min). The risk of all-cause death was significantly increased in AF patients with abruptly deteriorating kidney function.

Differences in outcomes between oral anticoagulation "new starters" and "switchers" in patients with nonvalvular atrial fibrillation: A pooled analysis of the AMADEUS and BOREALIS trials

BACKGROUND

To explore differences in outcomes between dose-adjusted vitamin K antagonists (VKAs) "new starters" and "switchers" in patients with nonvalvular atrial fibrillation (AF).

METHODS

A post hoc analysis was performed to assess the outcome differences between VKA "new starters" and "switchers" in AF patients using pooled individual patient data of AMADEUS and BOREALIS trials.

RESULTS

A total of 4169 AF patients were included in the present analysis, which included 1383 "VKA new starters" and 2786 "VKA switchers". VKA new starters had higher crude rates of all-cause mortality (P = .035) and cardiovascular death (P = .047) compared to switchers. On multivariable Cox regression analysis, both "new starters" and "switchers" showed nonsignificant trends for different risks of stroke/systemic thromboembolism (SE) (hazard ratio (HR): 1.66, 95%CI: 0.95-2.90, P = .08), major bleeding (HR: 1.25, 95% CI: 0.73-2.16, P = .42), and all-cause death (HR: 1.09, 95% CI: 0.75-1.57, P = .65). On Kaplan-Meier analysis, both groups had similar risks of stroke/systemic embolism (P = .09), major bleeding (P = .28), and all-cause death (P = .06).

CONCLUSIONS

In this post hoc analysis of clinical trial patients with AF, "new starters" and "switchers" for VKA initiation had nonstatistically significant rates of trial-adjudicated thromboembolism, major bleeding, and all-cause mortality.

A Propensity Score Matched Comparison of Clinical Outcomes in Atrial Fibrillation Patients Taking Vitamin K Antagonists: Comparing the "Real-World" vs Clinical Trials

OBJECTIVE

To investigate the incidence and risk of adverse clinical outcomes in a "real-world" cohort of patients with atrial fibrillation (AF) anticoagulated with vitamin K antagonists (VKAs) from the Murcia AF Project in comparison with the warfarin arm of the randomized clinical trial (RCT) AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation).

PATIENTS AND METHODS

We included 1361 patients with AF from the Murcia AF Project (recruitment from May 1, 2007, to December 1, 2007) and 2293 from the AMADEUS trial (started in September 2003 and primary completed in March 2006), all taking VKA treatment. After propensity score matching (PSM), we investigated differences in rates and risks of several events, including major bleeding, ischemic stroke, and all-cause mortality at 365 (interquartile range, 275-428) days of follow-up.

RESULTS

After PSM there were 1324 patients for the comparative analysis, whereby annual event rates for most adverse events were significantly higher in the "real-world" population. Cox regression analyses demonstrated that the risk of primary outcomes was also increased in the "real-world" (vs RCT: hazard ratio [HR], 6.32; 95% CI, 2.84-14.03 for major bleeding; HR, 3.56, 95% CI, 1.22-10.42 for ischemic stroke; HR, 5.13, 95% CI, 3.02-8.69 for all-cause mortality). The risk of all other adverse events was higher in the real-world cohort, except for cardiovascular mortality.

CONCLUSION

This study comparing the Murcia AF Project and the AMADEUS trial demonstrates that there is a great heterogeneity in both populations, which is translated into a higher risk of several adverse outcomes in the real-world cohort, including major bleeding, ischemic stroke, and mortality.

Comparison of the 2MACE and TIMI-AF Scores for Composite Clinical Outcomes in Anticoagulated Atrial Fibrillation Patients

BACKGROUND

Two risk scores have been developed to predict composite outcomes in atrial fibrillation (AF): the 2MACE and TIMI-AF scores. The aim of this study was to compare the predictive ability of these scores in 2 separate warfarin-treated cohorts (one 'real world', one clinical trial) of AF patients.

METHODS AND RESULTS

The 2MACE and TIMI-AF scores were calculated in the 'real-world' ATHERO-AF cohort (n=907), and in the randomized controlled AMADEUS trial (n=2,265). Endpoints were major adverse cardiovascular events (MACEs), net clinical outcomes (NCO) and a combination of them, namely "clinically relevant events" (CREs). ROC curves showed similar predictive ability for MACE for 2MACE and TIMI-AF, in both the ATHERO-AF (0.698 vs. 0.688, respectively P=0.783) and AMADEUS (0.657 vs. 0.569, respectively P=0.057) cohorts. Similarly, the TIMI-AF showed a comparable c-index with 2MACE for NCOs in the ATHERO-AF (0.676 vs. 0.667, P=0.737), and AMADEUS (0.666 vs. 0.663, P=0.859) cohorts. No differences were found between the 2 scores for the prediction of CREs (0.675 vs. 0.684, P=0.740 in ATHERO-AF and 0.669 vs. 0.667, P=0.889 in AMADEUS for 2MACE and TIMI-AF, respectively).

CONCLUSIONS

This study showed that the 2MACE and TIMI-AF scores had modest but significant predictive ability for composite outcomes in AF. The clinical usefulness of both scores was similar, but the 2MACE score may be simpler and easy to use.

Factor Xa inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in patients with atrial fibrillation

BACKGROUND

Factor Xa inhibitors and vitamin K antagonists (VKAs) are now recommended in treatment guidelines for preventing stroke and systemic embolic events in people with atrial fibrillation (AF). This is an update of a Cochrane review previously published in 2013.

OBJECTIVES

To assess the effectiveness and safety of treatment with factor Xa inhibitors versus VKAs for preventing cerebral or systemic embolic events in people with AF.

SEARCH METHODS

We searched the trials registers of the Cochrane Stroke Group and the Cochrane Heart Group (September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (August 2017), MEDLINE (1950 to April 2017), and Embase (1980 to April 2017). We also contacted pharmaceutical companies, authors and sponsors of relevant published trials. We used outcome data from marketing authorisation applications of apixaban, edoxaban and rivaroxaban that were submitted to regulatory authorities in Europe and the USA.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that directly compared the effects of long-term treatment (lasting more than four weeks) with factor Xa inhibitors versus VKAs for preventing cerebral and systemic embolism in people with AF.

DATA COLLECTION AND ANALYSIS

The primary efficacy outcome was the composite endpoint of all strokes and systemic embolic events. Two review authors independently extracted data, and assessed the quality of the trials and the risk of bias. We calculated a weighted estimate of the typical treatment effect across trials using the odds ratio (OR) with 95% confidence interval (CI) by means of a fixed-effect model. In case of moderate or high heterogeneity of treatment effects, we used a random-effects model to compare the overall treatment effects. We also performed a pre-specified sensitivity analysis excluding any open-label studies.

MAIN RESULTS

We included data from 67,688 participants randomised into 13 RCTs. The included trials directly compared dose-adjusted warfarin with either apixaban, betrixaban, darexaban, edoxaban, idraparinux, idrabiotaparinux, or rivaroxaban. The majority of the included data (approximately 90%) was from apixaban, edoxaban, and rivaroxaban.The composite primary efficacy endpoint of all strokes (both ischaemic and haemorrhagic) and non-central nervous systemic embolic events was reported in all of the included studies. Treatment with a factor Xa inhibitor significantly decreased the number of strokes and systemic embolic events compared with dose-adjusted warfarin in participants with AF (OR 0.89, 95% CI 0.82 to 0.97; 13 studies; 67,477 participants; high-quality evidence).Treatment with a factor Xa inhibitor significantly reduced the number of major bleedings compared with warfarin (OR 0.78, 95% CI 0.73 to 0.84; 13 studies; 67,396 participants; moderate-quality evidence). There was, however, statistically significant and high heterogeneity (I2 = 83%). When we repeated this analysis using a random-effects model, it did not show a statistically significant decrease in the number of major bleedings (OR 0.88, 95% CI 0.66 to 1.17). A pre-specified sensitivity analysis excluding all open-label studies showed that treatment with a factor Xa inhibitor significantly reduced the number of major bleedings compared with warfarin (OR 0.75, 95% CI 0.69 to 0.81), but high heterogeneity was also observed in this analysis (I2 = 72%). The same sensitivity analysis using a random-effects model also showed a statistically significant decrease in the number of major bleedings in participants treated with factor Xa inhibitors (OR 0.76, 95% CI 0.60 to 0.96).Treatment with a factor Xa inhibitor significantly reduced the risk of intracranial haemorrhages (ICHs) compared with warfarin (OR 0.50, 95% CI 0.42 to 0.59; 12 studies; 66,259 participants; high-quality evidence). We observed moderate, but statistically significant heterogeneity (I2 = 55%). The pre-specified sensitivity analysis excluding open-label studies showed that treatment with a factor Xa inhibitor significantly reduced the number of ICHs compared with warfarin (OR 0.47, 95% CI 0.40 to 0.56), with low, non-statistically significant heterogeneity (I2 = 27%).Treatment with a factor Xa inhibitor also significantly reduced the number of all-cause deaths compared with warfarin (OR 0.89, 95% 0.83 to 0.95; 10 studies; 65,624 participants; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Treatment with factor Xa inhibitors significantly reduced the number of strokes and systemic embolic events compared with warfarin in people with AF. The absolute effect of factor Xa inhibitors compared with warfarin treatment was, however, rather small. Factor Xa inhibitors also reduced the number of ICHs, all-cause deaths and major bleedings compared with warfarin, although the evidence for a reduction in the latter is less robust.

Management of Stroke risk in atrial fibrillation patients with bleeding on Oral Anticoagulation Therapy-Role of Left Atrial Appendage Closure, Octreotide and more

Background

Bleeding complications especially gastrointestinal bleeding remains a major challenge associated with oral anticoagulation therapy (OAT) and often leads clinicians to withdraw oral anticoagulation therapy (OAT) . This exposes patients to risk of stroke and systemic thromboembolism (STE). Novel oral anticoagulants (NOACs) have proved no better when it comes to bleeding events and in fact studies have shown that overall NOACs are associated with higher incidence of gastrointestinal (GI) bleeding compared to warfarin .

Objectives

In this review, we describe the difficulties encountered in managing OAT in patients with bleeding and strategies to maneuver around these bleeding complications particularly gastrointestinal bleeding secondary to arteriovenous malformations (AVM) and other vascular abnormalities.

Findings

Left atrial appendage closure (LAAC) has emerged as a very elegant and promising tool for stroke prevention in non-valvular atrial fibrillation (AF) patients who are intolerant to OAT. But the need for OAT post procedure for a brief period is becoming a major hurdle for clinicians to pursue in this direction in patients with recurrent gastrointestinal bleeds. And in majority of cases, recurrent or refractory gastrointestinal bleeds are usually secondary to arteriovenous malformations/angiodysplasias (AVM/AD). We suggest that the problem has to be approached by decreasing or eliminating the acute bleeding risk and closing the LAA in the long term, to enable the patients to come off of OAT and minimize the risk of recurrent bleeding.

Comparison of the CHADS2, CHA2DS2 -VASc and HAS-BLED scores for the prediction of clinically relevant bleeding in anticoagulated patients with atrial fibrillation: The AMADEUS trial

Many of the risk factors for stroke in atrial fibrillation (AF) are also important risk factors for bleeding. We tested the hypothesis that the CHADS2 and CHA2DS2-VASc scores (used for stroke risk assessment) could be used to predict serious bleeding, and that these scores would compare well against the HAS-BLED score, which is a specific risk score designed for bleeding risk assessment. From the AMADEUS trial, we focused on the trial’s primary safety outcome for serious bleeding, which was “any clinically relevant bleeding”. The predictive value of HAS-BLED/CHADS2/CHA2DS2-VASc were compared by area under the curve (AUC, a measure of the c-index) and the Net Reclassification Improvement (NRI). Of 2,293 patients on VKA, 251 (11%) experienced at least one episode of “any clinically relevant bleeding” during an average 429 days follow up period. Incidence of “any clinically relevant bleeding” rose with increasing HAS-BLED/CHADS2/CHA2DS2-VASc scores, but was statistically significant only for HAS-BLED (p<0.0001). Only HAS-BLED demonstrated significant discriminatory performance for “any clinically relevant bleeding” (AUC 0.60, p<0.0001). There were significant AUC-differences between HAS-BLED (which had the highest AUC) and both CHADS2 (p<0.001) and CHA2DS2VASc (p=0.001). The HAS-BLED score also demonstrated significant NRI for the outcome of “any clinically relevant bleeding” when compared with CHADS2 (p=0.001) and CHA2DS2-VASc (p=0.04). In conclusion, the HAS-BLED score demonstrated significant discriminatory performance for “any clinically relevant bleeding” in anticoagulated patients with AF, whilst the CHADS2 and CHA2DS2-VASc scores did not. Bleeding risk assessment should be made using a specific bleeding risk score such as HAS-BLED, and the stroke risk scores such as CHADS2 or CHA2DS2-VASc scores should not be used.

Do open label blinded outcome studies of novel anticoagulants versus warfarin have equivalent validity to those carried out under double-blind conditions?

Recent anticoagulants for stroke prevention in AF have been tested in active comparator controlled studies versus warfarin using two designs: double-blind, double-dummy and prospective randomised, open blinded endpoint (PROBE). The former requires elaborate procedures to maintain blinding, while PROBE does not. Outcomes of double-blind and PROBE designed studies of novel anticoagulants for AF, focusing on warfarin controls, were explored. Major, Phase III warfarin-controlled trials for stroke prevention in AF were identified. Odds ratios (ORs) of key outcomes for active comparators versus VKA and event rates for VKA arms were compared between designs, in context of baseline demographics and inclusion criteria. Identified trials studied five novel anticoagulants in three each of PROBE and double-blind design. For ORs of results across studies and outcomes, there was little pattern differentiating the two designs. Among VKA-control subjects, event rates for the primary outcome (stroke or systemic embolism) in PROBE trials at 1.74 %/year (95% confidence interval: 1.54–1.95) was not significantly different from that in double-blind trials, at 1.88 (1.73–2.03). Among other outcomes, VKA-treated subjects in both trial designs had similar event rates, apart from higher all-cause mortality in ROCKET AF, and lower myocardial infarction rates among the PROBE study patients. Although there are differences in outcome between PROBE and double blind trials, they do not appear to be design-related. The exacting requirements of double-blinding in AF trials may not be necessary.

Parenteral anticoagulants in heart disease: Current status and perspectives (Section II)

Anticoagulants are a mainstay of cardiovascular therapy, and parenteral anticoagulants have widespread use in cardiology, especially in acute situations. Parenteral anticoagulants include unfractionated heparin, low-molecular-weight heparins, the synthetic pentasaccharides fondaparinux, idraparinux and idrabiotaparinux, and parenteral direct thrombin inhibitors. The several shortcomings of unfractionated heparin and of low-molecular-weight heparins have prompted the development of the other newer agents. Here we review the mechanisms of action, pharmacological properties and side effects of parenteral anticoagulants used in the management of coronary heart disease treated with or without percutaneous coronary interventions, cardioversion for atrial fibrillation, and prosthetic heart valves and valve repair. Using an evidence-based approach, we describe the results of completed clinical trials, highlight ongoing research with currently available agents, and recommend therapeutic options for specific heart diseases.

The importance of mean time in therapeutic range for complication rates in warfarin therapy of patients with atrial fibrillation: A systematic review and meta-regression analysis

Background

\Anticoagulation is used for stroke prophylaxis in non-valvular atrial fibrillation, amongst other by use of the vitamin K antagonist, warfarin. Quality in warfarin therapy is often summarized by the time patients spend within the therapeutic range (percent time in therapeutic range, TTR). The correlation between TTR and the occurrence of complications during warfarin therapy has been established, but the influence of patient characteristics in that respect remains undetermined. The objective of the present papers was to examine the association between mean TTR and complication rates with adjustment for differences in relevant patient cohort characteristics.

Methods

A systematic literature search was conducted in MEDLINE and Embase (2005–2015) to identify eligible studies reporting on use of warfarin therapy by patients with non-valvular atrial fibrillation and the occurrence of hemorrhage and thromboembolism. Both randomized controlled trials and observational cohort studies were included. The association between the reported mean TTR and major bleeding and stroke/systemic embolism was analyzed by random-effects meta-regression with and without adjustment for relevant clinical cohort characteristics. In the adjusted meta-regressions, the impact of mean TTR on the occurrence of hemorrhage was adjusted for the mean age and the proportion of populations with prior stroke or transient ischemic attack. In the adjusted analyses on thromboembolism, the proportion of females was, furthermore, included.

Results

Of 2169 papers, 35 papers met pre-specified inclusion criteria, holding relevant information on 31 patient cohorts. In univariable meta-regression, increasing mean TTR was significantly associated with a decreased rate of both major bleeding and stroke/systemic embolism. However, after adjustment mean TTR was no longer significantly associated with stroke/systemic embolism. The proportion of residual variance composed by between-study heterogeneity was substantial for all analyses.

Conclusions

Although higher mean TTR in warfarin therapy was associated with lower complication rates in atrial fibrillation, the strength of the association was decreased when adjusting for differences in relevant clinical characteristics of the patient cohorts. This study suggests that mainly the safety of warfarin therapy increases with higher mean TTR, whereas effectiveness appears not to be substantially improved.

Due to the limitations immanent in the meta-regression methods, the results of the present study should be interpreted with caution. Further research on the association between the quality of warfarin therapy and risk of complications is warranted with adjustment for clinically relevant characteristics.

Effect of Genotype-Guided Warfarin Dosing on Clinical Events and Anticoagulation Control Among Patients Undergoing Hip or Knee Arthroplasty: The GIFT Randomized Clinical Trial

IMPORTANCE

Warfarin use accounts for more medication-related emergency department visits among older patients than any other drug. Whether genotype-guided warfarin dosing can prevent these adverse events is unknown.

OBJECTIVE

To determine whether genotype-guided dosing improves the safety of warfarin initiation.

DESIGN, SETTING, AND PATIENTS

The randomized clinical Genetic Informatics Trial (GIFT) of Warfarin to Prevent Deep Vein Thrombosis included patients aged 65 years or older initiating warfarin for elective hip or knee arthroplasty and was conducted at 6 US medical centers. Enrollment began in April 2011 and follow-up concluded in October 2016.

INTERVENTIONS

Patients were genotyped for the following polymorphisms: VKORC1-1639G>A, CYP2C9*2, CYP2C9*3, and CYP4F2 V433M. In a 2 × 2 factorial design, patients were randomized to genotype-guided (n = 831) or clinically guided (n = 819) warfarin dosing on days 1 through 11 of therapy and to a target international normalized ratio (INR) of either 1.8 or 2.5. The recommended doses of warfarin were open label, but the patients and clinicians were blinded to study group assignment.

MAIN OUTCOMES AND MEASURES

The primary end point was the composite of major bleeding, INR of 4 or greater, venous thromboembolism, or death. Patients underwent a screening lower-extremity duplex ultrasound approximately 1 month after arthroplasty.

RESULTS

Among 1650 randomized patients (mean age, 72.1 years [SD, 5.4 years]; 63.6% women; 91.0% white), 1597 (96.8%) received at least 1 dose of warfarin therapy and completed the trial (n = 808 in genotype-guided group vs n = 789 in clinically guided group). A total of 87 patients (10.8%) in the genotype-guided group vs 116 patients (14.7%) in the clinically guided warfarin dosing group met at least 1 of the end points (absolute difference, 3.9% [95% CI, 0.7%-7.2%], P = .02; relative rate [RR], 0.73 [95% CI, 0.56-0.95]). The numbers of individual events in the genotype-guided group vs the clinically guided group were 2 vs 8 for major bleeding (RR, 0.24; 95% CI, 0.05-1.15), 56 vs 77 for INR of 4 or greater (RR, 0.71; 95% CI, 0.51-0.99), 33 vs 38 for venous thromboembolism (RR, 0.85; 95% CI, 0.54-1.34), and there were no deaths.

CONCLUSIONS AND RELEVANCE

Among patients undergoing elective hip or knee arthroplasty and treated with perioperative warfarin, genotype-guided warfarin dosing, compared with clinically guided dosing, reduced the combined risk of major bleeding, INR of 4 or greater, venous thromboembolism, or death. Further research is needed to determine the cost-effectiveness of personalized warfarin dosing.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01006733.

Risks of postextraction bleeding after receiving direct oral anticoagulants or warfarin: a retrospective cohort study

OBJECTIVE

The effect of direct oral anticoagulants (DOACs) on the risk of bleeding after tooth extraction remains unclear. This study aimed to evaluate the incidence of postextraction bleeding among patients who received DOAC and vitamin K antagonists (VKAs), such as warfarin.

DESIGN

This study was a retrospective cohort analysis. Incidence rates and propensity score-matched regression models were used to compare the risks of bleeding after tooth extractions involving DOACs and VKAs.

SETTING

The study took place in a single university hospital in Japan.

PARTICIPANTS

Between April 2013 and April 2015, 543 patients underwent a total of 1196 simple tooth extractions.

PRIMARY OUTCOME MEASURE

The primary outcome measure was the occurrence of postextraction bleeding, which was defined as bleeding that could not be stopped by biting down on gauze and required medical treatment between 30 min and 7 days after the extraction.

RESULTS

A total of 1196 tooth extractions (634 procedures) in 541 patients fulfilled the study criteria, with 72 extractions (41 procedures) involving DOACs, 100 extractions (50 procedures) involving VKAs and 1024 extractions (543 procedures) involving no anticoagulants. The incidences of postextraction bleeding per tooth for the DOAC, VKA and no anticoagulant extractions were 10.4%, 12.0% and 0.9%, respectively. The incidences of postextraction bleeding per procedure for DOACs, VKAs and no anticoagulants were 9.7%, 10.0% and 1.1%, respectively. In comparison to the VKA extractions, the DOAC extractions did not significantly increase the risk of postextraction bleeding (OR 0.69, 95% CIs 0.24 to 1.97; p=0.49).

CONCLUSIONS

The risk of postextraction bleeding was similar for DOAC and VKA extractions.

Pentasaccharides for the prevention of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a common condition with potentially serious and life-threatening consequences. The standard method of thromboprophylaxis uses an anticoagulant such as low molecular weight heparin (LMWH) or warfarin. In recent years, another type of anticoagulant, pentasaccharide, an indirect factor Xa inhibitor, has shown good anticoagulative effect in clinical trials. Three types of pentasaccharides are available: short-acting fondaparinux, long-acting idraparinux and idrabiotaparinux. Pentasaccharides cause little heparin-induced thrombocytopenia and are better tolerated than unfractionated heparin, LMWH and warfarin. However, no consensus has been reached on whether pentasaccharides are superior or inferior to other anticoagulative methods.

OBJECTIVES

To assess effects of pentasaccharides versus other methods of thromboembolic prevention (thromboprophylaxis) in people who require anticoagulant treatment to prevent venous thromboembolism.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (last searched March 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2). The CIS searched trial databases for details of ongoing and unpublished studies. Review authors searched LILACS (Latin American and Caribbean Health Sciences) and the reference lists of relevant studies and reviews identified by electronic searches.

SELECTION CRITERIA

We included randomised controlled trials on any type of pentasaccharide versus other anticoagulation methods (pharmaceutical or mechanical) for VTE prevention.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed methodological quality and extracted data in predesigned tables.

MAIN RESULTS

We included in this review 25 studies with a total of 21,004 participants. All investigated fondaparinux for VTE prevention; none investigated idraparinux or idrabiotaparinux. Studies included participants undergoing abdominal surgery, thoracic surgery, bariatric surgery or coronary bypass surgery; acutely ill hospitalised medical patients; people requiring rigid or semirigid immobilisation; and those with superficial venous thrombosis. Most studies focused on orthopaedic patients. We lowered the quality of the evidence because of heterogeneity between studies and a small number of events causing imprecision.When comparing fondaparinux with placebo, we found less total VTE (risk ratio (RR) 0.24, 95% confidence interval (CI) 0.15 to 0.38; 5717 participants; 8 studies; I2 = 64%; P < 0.00001), less symptomatic VTE (RR 0.15, 95% CI 0.06 to 0.36; 6503 participants; 8 studies; I2 = 0%; P < 0.0001), less total DVT (RR 0.25, 95% CI 0.15 to 0.40; 5715 participants; 8 studies; I2 = 67%; P < 0.00001), less proximal DVT (RR 0.12, 95% CI 0.04 to 0.39; 2746 participants; 7 studies; I2 = 64%; P = 0.0004) and less total pulmonary embolism (PE) (RR 0.16, 95% CI 0.04 to 0.62; 6412 participants; 8 studies; I2 = 0%; P = 0.008) in the fondaparinux group. The quality of the evidence was moderate for total VTE, total DVT and proximal DVT, and high for symptomatic VTE and total PE.When fondaparinux was compared with LMWH, analyses indicated that fondaparinux reduced total VTE and DVT (RR 0.55, 95% CI 0.42 to 0.73; 9339 participants; 11 studies; I2 = 64%; P < 0.0001; and RR 0.54, 95% CI 0.40 to 0.71; 9356 participants; 10 studies; I2 = 67%; P < 0.0001, respectively), and showed a trend toward reduced proximal DVT (RR 0.58, 95% CI 0.33 to 1.02; 8361 participants; 9 studies; I2 = 53%; P = 0.06). Symptomatic VTE (RR 1.03, 95% CI 0.65 to 1.63; 12240 participants; 9 studies; I2 = 35%; P = 0.90) and total PE (RR 1.24, 95% CI 0.65 to 2.34; 12350 participants; 10 studies; I2 = 0%; P = 0.51) indicated no difference between fondaparinux and LMWH. The quality of the evidence was moderate for total VTE, symptomatic VTE, total DVT and total PE, and low for proximal DVT.We showed that fondaparinux increased major bleeding compared with both placebo and LWMH (RR 2.56, 95% CI 1.48 to 4.44; 6659 participants; 8 studies; I2 = 0%; P = 0.0008; moderate-quality evidence; and RR 1.38, 95% CI 1.09 to 1.75; 12,501 participants; 11 studies; I2 = 24%; P = 0.008; high-quality evidence, respectively). All-cause mortality was not different between fondaparinux and placebo or LMWH (RR 0.76, 95% CI 0.48 to 1.22; 6674 participants; 8 studies; I2 = 14%; P = 0.26; moderate-quality evidence; and RR 0.88, 95% CI 0.63 to 1.22; 12,400 participants; 11 studies; I2 = 0%; P = 0.44; moderate-quality evidence, respectively).One study compared fondaparinux with variable and fixed (1 mg per day) doses of warfarin after elective hip or knee replacement surgery and showed no difference in primary and secondary outcomes between fondaparinux and both variable and fixed doses of warfarin. The quality of the evidence was very low. One small study compared fondaparinux with edoxaban in patients with severe renal impairment undergoing lower-limb orthopaedic surgery and reported no thromboembolic events, major bleeding events or deaths in either group. The quality of the evidence was very low. One small study compared fondaparinux with mechanical thromboprophylaxis. Results showed no difference in total VTE and total DVT between fondaparinux and mechanical thromboprophylaxis. This study reported no cases pertaining to the other outcomes of this review. The quality of the evidence was low.There were insufficient studies to permit meaningful conclusions for subgroups of clinical conditions other than orthopaedic surgery.

AUTHORS' CONCLUSIONS

Moderate to high quality evidence shows that fondaparinux is effective for short-term prevention of VTE when compared with placebo. It can reduce total VTE, DVT, total PE and symptomatic VTE, and does not demonstrate a reduction in deaths compared with placebo. Low to moderate quality evidence shows that fondaparinux is more effective for short-term VTE prevention when compared with LMWH. It can reduce total VTE and total DVT and does not demonstrate a reduction in deaths when compared with LMWH. However, at the same time, moderate to high quality evidence shows that fondaparinux increases major bleeding when compared with placebo and LMWH. Therefore, when fondaparinux is chosen for the prevention of VTE, attention should be paid to the person's bleeding and thrombosis risks. Most data were derived from patients undergoing orthopaedic surgery. Therefore, the conclusion predominantly pertains to these patients. Data on fondaparinux for other clinical conditions are sparse.

Exploratory Network Meta Regression Analysis of Stroke Prevention in Atrial Fibrillation Fails to Identify Any Interactions with Treatment Effect

BACKGROUND

Patients with atrial fibrillation are at a greater risk of stroke and therefore the main goal for treatment of patients with atrial fibrillation is to prevent stroke from occurring. There are a number of different stroke prevention treatments available to include warfarin and novel oral anticoagulants. Previous network meta-analyses of novel oral anticoagulants for stroke prevention in atrial fibrillation acknowledge the limitation of heterogeneity across the included trials but have not explored the impact of potentially important treatment modifying covariates.

OBJECTIVES

To explore potentially important treatment modifying covariates using network meta-regression analyses for stroke prevention in atrial fibrillation.

METHODS

We performed a network meta-analysis for the outcome of ischaemic stroke and conducted an exploratory regression analysis considering potentially important treatment modifying covariates. These covariates included the proportion of patients with a previous stroke, proportion of males, mean age, the duration of study follow-up and the patients underlying risk of ischaemic stroke.

RESULTS

None of the covariates explored impacted relative treatment effects relative to placebo. Notably, the exploration of 'study follow-up' as a covariate supported the assumption that difference in trial durations is unimportant in this indication despite the variation across trials in the network.

CONCLUSION

This study is limited by the quantity of data available. Further investigation is warranted, and, as justifying further trials may be difficult, it would be desirable to obtain individual patient level data (IPD) to facilitate an effort to relate treatment effects to IPD covariates in order to investigate heterogeneity. Observational data could also be examined to establish if there are potential trends elsewhere. The approach and methods presented have potentially wide applications within any indication as to highlight the potential benefit of extending decision problems to include additional comparators outside of those of primary interest to allow for the exploration of heterogeneity.

Evaluation of the HAS-BLED, ATRIA, and ORBIT Bleeding Risk Scores in Patients with Atrial Fibrillation Taking Warfarin

OBJECTIVES

Various bleeding risk prediction schemes, such as the Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized Ratio, Elderly, Drugs/alcohol (HAS-BLED), Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA), and Outcomes Registry for Better Informed Treatment (ORBIT) scores, have been proposed in patients with atrial fibrillation. We compared the relative predictive values of these bleeding risk scores for clinically relevant bleeding and the relationship of ATRIA and ORBIT scores to the quality of anticoagulation control on warfarin, as reflected by time in therapeutic range.

METHODS

We conducted a post hoc ancillary analysis of clinically relevant bleeding and major bleeding events among 2293 patients receiving warfarin therapy in the AMADEUS trial.

RESULTS

Only HAS-BLED was significantly predictive for clinically relevant bleeding, and all 3 risk scores were predictive for major bleeding. The predictive performance of HAS-BLED was modest, as reflected by c-indexes of 0.59 (P < .001) and 0.65 (P < .002) for clinically relevant bleeding and major bleeding, respectively. The HAS-BLED score performed better than the ATRIA (P = .002) or ORBIT (P = .001) score in predicting any clinically relevant bleeding. Only the HAS-BLED score was significantly associated with the risk for both bleeding outcomes on Cox regression analysis (any clinically relevant bleeding: hazard ratio, 1.85; 95% confidence interval, 1.43-2.40, P < .001; major bleeding: hazard ratio, 2.40; 95% confidence interval, 1.28-4.52; P = .007). There were strong inverse correlations of ATRIA and ORBIT scores to time in therapeutic range as a continuous variable (low risk ATRIA, r = -0.96; P = .003; ORBIT, r = -0.96; P = .003). Improvement in the predictive performance for both ATRIA and ORBIT scores for any clinically relevant bleeding was achieved by adding time in therapeutic range to both scores, with significant differences in c-indexes (P = .001 and P = .002, respectively), net reclassification improvement, and integrated discriminant improvement (both P < .001).

CONCLUSIONS

All 3 bleeding risk prediction scores demonstrated modest predictive ability for bleeding outcomes, although the HAS-BLED score performed better than the ATRIA or ORBIT score. Significant improvements in both ATRIA and ORBIT score prediction performances were achieved by adding time in therapeutic range to both scores.

Female Sex, Time in Therapeutic Range, and Clinical Outcomes in Atrial Fibrillation Patients Taking Warfarin

BACKGROUND AND PURPOSE

Female patients have higher risk for stroke than male patients in nonanticoagulated atrial fibrillation patients, but limited data are available on sex differences in stroke and bleeding outcomes among patients with anticoagulated atrial fibrillation on warfarin, especially in relation to quality of anticoagulation control, as reflected by the time in therapeutic range (TTR).

METHODS

We investigated adverse outcomes in females (n=791) and males (n=1501) among 2292 patients with atrial fibrillation taking warfarin arm in the AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation) trial.

RESULTS

The combined end point of cardiovascular death and stroke/systemic embolism (SSE) was similar in females versus males. There was no sex differences in either cardiovascular death or SSE. Compared with males, females had a lower risk of major bleeding (hazard ratio, 0.39; 95% confidence interval, 0.18-0.87; P=0.02). No differences were seen in mortality and stroke outcomes between females and males either in the prespecified age subgroups or in relation to TTR categories. TTR was negatively correlated with any clinically relevant bleeding in both females (r=-0.86; P=0.03) and males (r=-0.94; P=0.005). On Cox regression, TTR (but not female sex) emerged as an independent predictor for combined cardiovascular death/SSE and clinically relevant bleeding events.

CONCLUSION

Anticoagulated female patients with atrial fibrillation had a similar rate of cardiovascular death and SSE, but a lower risk of major bleeding, compared with males. TTR (but not female sex) was an independent predictor for combined cardiovascular death and SSE and clinically relevant bleeding events.

Relationship of Age With Stroke and Death in Anticoagulated Patients With Nonvalvular Atrial Fibrillation

Background and Purpose—

The prevalence of atrial fibrillation increases with age, but age-specific data on the incidence of stroke and death in anticoagulated patients with atrial fibrillation are more limited, particularly with regard to comparisons of relative risks of clinical outcomes between the different age strata in relation to quality of anticoagulation control among warfarin users.

Methods—

We investigated the incidence of adverse outcomes between tertiles of age groups (age, <67 [n=722]; age, 67–74 [n=747]; and age, ≥75 [n=824]) in 2293 patients with atrial fibrillation participating in warfarin arm in the AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation) trial. The average time in therapeutic range was calculated as a measure of anticoagulation control and related to clinical outcomes.

Results—

Absolute rates for stroke/systemic embolism (SSE), cardiovascular death, or any clinically relevant bleeding increased with increasing age strata. The combined end point of cardiovascular death and SSE was the highest in the top tertile (adjusted hazard ratio, 2.63; 95% confidence interval, 1.23–5.63) compared with the middle and lowest tertiles ( P for trend=0.01). For bleeding, there was no significant difference in relative risks between the age strata ( P for trend=0.55 in the warfarin group and in the warfarin group with time in therapeutic range ≥60%, P for trend=0.60). The quality of anticoagulation control (time in therapeutic range) significantly correlated with any clinically relevant bleeding ( r =−0.91; P <0.001) and cardiovascular death/SSE rates ( r =−0.76; P =0.01).

Conclusions—

Elderly patients with atrial fibrillation have higher absolute risks of cardiovascular death, SSE, and bleeding, but relative risks of clinically relevant bleeding are not significantly different with increasing age strata. A significant inverse relationship between time in therapeutic range and bleeding and cardiovascular death/SSE emphasizes the importance of good quality anticoagulation control.

Residual Risk of Stroke and Death in Anticoagulated Patients According to the Type of Atrial Fibrillation

Background and Purpose—

Atrial fibrillation (AF) and heart failure frequently coexist and are associated with increased morbidity and mortality. We investigated the prognosis of anticoagulated patients with permanent AF and nonpermanent AF according to preexisting heart failure in the AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation) trial.

Methods—

The primary outcome was a composite of cardiovascular death and stroke or systemic embolism, analyzed using a Cox proportional hazards model, adjusted for baseline age, sex, diabetes mellitus, hypertension, creatinine, and previous cardiovascular diseases. The median follow-up was 11.6 months (interquartile range, 6.2–15.2).

Results—

Nonpermanent AF was present in 2072 patients (46% of cohort), of which 339 (16%) had preexisting heart failure. A total of 2484 patients had permanent AF (54% of cohort), with a higher burden of heart failure including 730 patients (29%; P <0.001). Overall, death because of cardiovascular causes occurred in 57 patients and 45 had stroke or systemic embolism (1.4/100 person-years for each). Overall, the adjusted incidence of the composite outcome was higher in patients with permanent AF than in patients with nonpermanent AF. In multivariate analysis, permanency of AF, creatinine, prior cerebrovascular events, and previous coronary disease were independently associated with the primary outcome. The hazard ratio for permanent versus nonpermanent AF was 1.68 (95% confidence interval, 1.08–2.55; P =0.02). The presence of heart failure increased the risk of adverse outcomes in a similar way in both permanent and nonpermanent AF (interaction P value=0.76).

Conclusions—

The risk of cardiovascular death, stroke, or systemic embolism is higher in anticoagulated patients with permanent AF than in those with nonpermanent AF, regardless of preexisting heart failure.

Comparative efficacy and safety of novel oral anticoagulants in patients with atrial fibrillation: A network meta-analysis with the adjustment for the possible bias from open label studies

BACKGROUND

This study was designed to compare efficacy and safety among novel oral anticoagulants (NOACs), which have not been directly compared in randomized control trials to date.

METHOD

We performed network meta-analyses of randomized control trials in preventing thromboembolic events and major bleeding in patients with atrial fibrillation. PubMed, Embase, and the Cochrane Database of Systematic Reviews for published studies and various registries of clinical trials for unpublished studies were searched for 2002-2013. All phase III randomized controlled trials (RCTs) of NOACs (apixaban, edoxaban, dabigatran, rivaroxaban), idraparinux, and ximelagatran were reviewed.

RESULTS

A systematic literature search identified nine phase III RCTs for primary analyses. The efficacy of each NOAC was similar with respect to our primary composite endpoint following adjustment for open label designs [odds ratios (ORs) versus vitamin K antagonists: apixaban 0.79; dabigatran 150mg 0.77; edoxaban 60mg 0.87; rivaroxaban 0.86] except for dabigatran 110mg and edoxaban 30mg. Apixaban and edoxaban 30mg and 60mg had significantly fewer major bleeding events than dabigatran 150mg, ricvaroxaban, and vitamin K antagonists. All NOACs were similar in reducing secondary endpoints with the exception of dabigatran 110mg and 150mg which were associated with a significantly greater incidence of myocardial infarction compared to apixaban, edoxaban 60mg, and rivaroxaban.

CONCLUSIONS

Our indirect comparison with adjustment for study design suggests that the efficacy of the examined NOACs is similar across drugs, but that some differences in safety and risk of myocardial infarction exist, and that open label study designs appear to overestimate safety and treatment efficacy. Differences in study design should be taken into account in the interpretation of results from RCTs of NOACs.

Balancing ischaemia and bleeding risks with novel oral anticoagulants

Vitamin K antagonists (VKAs) have long been the standard of care for treatment of venous thromboembolism (VTE), and thromboprophylaxis in atrial fibrillation (AF). Despite their efficacy, their use requires frequent monitoring and is complicated by drug-drug interactions and the need to maintain a narrow therapeutic window. Since 2009, novel oral anticoagulants (NOACs), including the direct thrombin inhibitor dabigatran and the direct factor Xa inhibitors apixaban, edoxaban, and rivaroxaban, have become alternative options to VKAs owing to their predictable and safe pharmacological profiles. The overall clinical effect of these drugs, which is a balance between ischaemic benefit and bleeding harm, varies according to the clinical scenario. As adjunctive therapy to dual antiplatelet therapy in patients with acute coronary syndrome, NOACs are associated with incremental bleeding risks and modest benefits. For treatment of VTE, NOACs have a safer profile than VKAs and a similar efficacy. In thromboprophylaxis in AF, NOACs are associated with the greatest benefits by reducing both ischaemic events and haemorrhagic complications and might reduce mortality compared with VKAs. The role of NOACs continues to evolve as these drugs are evaluated in different patient populations, including those with renal impairment or with AF and undergoing percutaneous coronary intervention.

Bleeding risk prediction models in atrial fibrillation

Novel, nonvitamin K antagonist oral anticoagulants (OACs) have demonstrated similar or superior efficacy to warfarin for ischemic stroke prevention in patients with atrial fibrillation (AF). As the prevalence of AF rises in a growing elderly population, these agents are becoming central to the routine practice of clinicians caring for these patients. Though the benefits are clear, the decision to treat the elderly patient with AF with long-term oral OACs is often a dilemma for the clinician mindful of the risk of major bleeding. Several bleeding risk prediction models have been created to help the clinician identify patients for whom the risk of bleeding is high, and would potentially outweigh the benefits of OAC therapy. In this review, we discuss the features of 8 bleeding risk prediction models, including the recently described HEMORR2HAGES, HAS-BLED, and ATRIA models, and approaches to assessing bleeding risk in clinical practice.

Comparison of idrabiotaparinux with vitamin K antagonists for prevention of thromboembolism in patients with atrial fibrillation: the Borealis-Atrial Fibrillation Study

BACKGROUND

Idrabiotaparinux, a long-acting inhibitor of factor Xa, was shown to be effective in the treatment of patients with venous thromboembolism.

OBJECTIVE

To assess non-inferiority for the efficacy of idrabiotaparinux versus warfarin in patients with atrial fibrillation (AF) at risk of stroke and systemic embolism. Bleeding was also assessed.

METHODS

This randomized, double-blind trial enrolled patients with electrocardiogram-documented AF. Idrabiotaparinux was administered weekly via subcutaneous injection, and warfarin was administered daily with dose adjustment to maintain the international normalized ratio between 2.0 and 3.0. Each idrabiotaparinux injection was 3 mg for the first 7 weeks, followed by 2 mg thereafter, except in patients with a creatinine clearance of 30-50 mL min(-1) or aged ≥ 75 years. The patients received 1.5 mg after the first 7 weeks. The efficacy outcome was the composite of all fatal or non-fatal strokes and systemic embolism. The safety outcome was clinically relevant bleeding (major and clinically relevant non-major bleeding).

RESULTS

The study was terminated prematurely by the sponsor for strategic/commercial, not scientific, reasons, with 39% of the planned number of patients included and an average duration of treatment of 240 days. Of the 1886 idrabiotaparinux recipients, 20 developed stroke or systemic embolism (1.5% per year), whereas this occurred in 22 of the 1887 warfarin patients (1.6% per year, hazard ratio 0.98, 95% confidence interval 0.49-1.66). The annual incidence of bleeding was 6.1% in the idrabiotaparinux and 10.0% in the warfarin group (hazard ratio 0.61, 95% confidence interval 0.46-0.81).

CONCLUSION

If anything, despite its early termination, the idrabiotaparinux regimen studied suggested a comparable efficacy to dose-adjusted warfarin, with a lower bleeding risk.

New oral anticoagulants may be particularly useful for asian stroke patients

Atrial fibrillation (AF) is an emerging epidemic in both high-income and low-income countries, mainly because of global population aging. Stroke is a major complication of AF, and AF-related ischemic stroke is more disabling and more fatal than other types of ischemic stroke. However, because of concerns about bleeding complications, particularly intracranial hemorrhage, and the limitations of a narrow therapeutic window, warfarin is underused. Four large phase III randomized controlled trials in patients with non-valvular AF (RE-LY, ROCKET-AF, ARISTOTLE, and ENGAGE-AF-TIMI 48) demonstrated that new oral anticoagulants (NOACs) are superior or non-inferior to warfarin as regards their efficacy in preventing ischemic stroke and systemic embolism, and superior to warfarin in terms of intracranial hemorrhage. Among AF patients receiving warfarin, Asians compared to non-Asians are at higher risk of stroke or systemic embolism and are also more prone to develop major bleeding complications, including intracranial hemorrhage. The extra benefit offered by NOACs over warfarin appears to be greater in Asians than in non-Asians. In addition, Asians are less compliant, partly because of the frequent use of herbal remedies. Therefore, NOACs compared to warfarin may be safer and more useful in Asians than in non-Asians, especially in stroke patients. Although the use of NOACs in AF patients is rapidly increasing, guidelines for the insurance reimbursement of NOACs have not been resolved, partly because of insufficient understanding of the benefit of NOACs and partly because of cost concerns. The cost-effectiveness of NOACs has been well demonstrated in the healthcare settings of developed countries, and its magnitude would vary depending on population characteristics as well as treatment cost. Therefore, academic societies and regulatory authorities should work together to formulate a scientific healthcare policy that will effectively reduce the burden of AF-related stroke in this rapidly aging society.

Influence of sex on risk of bleeding in anticoagulated patients: a systematic review and meta-analysis

BACKGROUND

The risk of bleeding on anticoagulation varies between patients. It is uncertain whether sex influences this risk.

OBJECTIVES

To determine if the risk of major bleeding differs between men and women receiving anticoagulation for atrial fibrillation or venous thromboembolism(VTE).

METHODS

We searched MEDLINE, EMBASE, and Cochrane databases, and relevant conference proceedings, until February 2013. We included randomized controlled trials and prospective cohort studies of patients on therapeutic anticoagulation for atrial fibrillation or VTE. Two reviewers independently extracted data. The relative risk of bleeding in men compared to women was pooled using a random-effects model.

RESULTS

Forty-two studies including 94 293 patients were eligible; 78 044 patients (83%) had atrial fibrillation; 16 156 patients (17%) had VTE; 37 250 patients were women (40%); and there were 4147 major bleeds. The relative risk of major bleeding for men vs. women was 1.02(95% CI 0.95–1.10; P = 0.27 for heterogeniety). The relative risk was 1.02 (95% CI 0.95–1.09) in patients with atrial fibrillation and 0.80 (95% CI 0.65–0.98) in patients with VTE (P = 0.03 for subgroup effect). Type of anticoagulant,intensity of anticoagulation, and whether patients began or were already established on anticoagulants at enrollment did not influence the relative risk of major bleeding in men compared to women.

CONCLUSIONS

The risk of major bleeding on anticoagulation appears to be the same in men and women, particularly if patients have atrial fibrillation. This finding is less certain for patients with VTE, in whom the risk of bleeding may be marginally lower in men compared to in women.

Direct thrombin inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in people with non-valvular atrial fibrillation

BACKGROUND

Chronic anticoagulation with vitamin K antagonists (VKAs) prevents ischaemic stroke and systemic embolism in people with non-valvular atrial fibrillation (AF) but dose adjustment, coagulation monitoring and bleeding limits its use. Direct thrombin inhibitors (DTIs) are under investigation as potential alternatives.

OBJECTIVES

To assess (1) the comparative efficacy of long-term anticoagulation using DTIs versus VKAs on vascular deaths and ischaemic events in people with non-valvular AF, and (2) the comparative safety of chronic anticoagulation using DTIs versus VKAs on (a) fatal and non-fatal major bleeding events including haemorrhagic strokes, (b) adverse events other than bleeding and ischaemic events that lead to treatment discontinuation and (c) all-cause mortality in people with non-valvular AF.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (July 2013), the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, May 2013), MEDLINE (1950 to July 2013), EMBASE (1980 to October 2013), LILACS (1982 to October 2013) and trials registers (September 2013). We also searched the websites of clinical trials and pharmaceutical companies and handsearched the reference lists of articles and conference proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing DTIs versus VKAs for prevention of stroke and systemic embolism in people with non-valvular AF.

DATA COLLECTION AND ANALYSIS

All three review authors independently performed data extraction and assessment of risk of bias. Primary analyses compared all DTIs combined versus warfarin. We performed post hoc analyses excluding ximelagatran because this drug was withdrawn from the market owing to safety concerns.

MAIN RESULTS

We included eight studies involving a total of 27,557 participants with non-valvular AF and one or more risk factors for stroke; 26,601 of them were assigned to standard doses groups and included in the primary analysis. The DTIs: dabigatran 110 mg twice daily and 150 mg twice daily (three studies, 12,355 participants), AZD0837 300 mg once per day (two studies, 233 participants) and ximelagatran 36 mg twice per day (three studies, 3726 participants) were compared with the VKA warfarin (10,287 participants). Overall risk of bias and statistical heterogeneity of the studies included were low.The odds of vascular death and ischaemic events were not significantly different between all DTIs and warfarin (odds ratio (OR) 0.94, 95% confidence interval (CI) 0.85 to 1.05). Sensitivity analysis by dose of dabigatran on reduction in ischaemic events and vascular mortality indicated that dabigatran 150 mg twice daily was superior to warfarin although the effect estimate was of borderline statistical significance (OR 0.86, 95% CI 0.75 to 0.99). Sensitivity analyses by other factors did not alter the results. Fatal and non-fatal major bleeding events, including haemorrhagic strokes, were less frequent with the DTIs (OR 0.87, 95% CI 0.78 to 0.97). Adverse events that led to discontinuation of treatment were significantly more frequent with the DTIs (OR 2.18, 95% CI 1.82 to 2.61). All-cause mortality was similar between DTIs and warfarin (OR 0.91, 95% CI 0.83 to 1.01).

AUTHORS' CONCLUSIONS

DTIs were as efficacious as VKAs for the composite outcome of vascular death and ischaemic events and only the dose of dabigatran 150 mg twice daily was found to be superior to warfarin. DTIs were associated with fewer major haemorrhagic events, including haemorrhagic strokes. Adverse events that led to discontinuation of treatment occurred more frequently with the DTIs. We detected no difference in death from all causes.

Meta-analysis of randomized controlled trials on risk of myocardial infarction from the use of oral direct thrombin inhibitors

Dabigatran has been associated with greater risk of myocardial infarction (MI) than warfarin. It is unknown whether the increased risk is unique to dabigatran, an adverse effect shared by other oral direct thrombin inhibitors (DTIs), or the result of a protective effect of warfarin against MI. To address these questions, we systematically searched MEDLINE and performed a meta-analysis on randomized trials that compared oral DTIs with warfarin for any indication with end point of MIs after randomization. We furthermore performed a secondary meta-analysis on atrial fibrillation stroke prevention trials with alternative anticoagulants compared with warfarin with end point of MIs after randomization. A total of 11 trials (39,357 patients) that compared warfarin to DTIs (dabigatran, ximelagatran, and AZD0837) were identified. In these trials, patients treated with oral DTIs were more likely to experience an MI than their counterparts treated with warfarin (285 of 23,333 vs 133 of 16,024, odds ratio 1.35, 95% confidence interval 1.10 to 1.66, p = 0.005). For secondary analysis, 8 studies (69,615 patients) were identified that compared warfarin with alternative anticoagulant including factor Xa inhibitors, DTIs, aspirin, and clopidogrel. There was no significant advantage in the rate of MIs with the use of warfarin versus comparators (odds ratio 1.06, 95% confidence interval 0.85 to 1.34, p = 0.59). In conclusion, our data suggest that oral DTIs were associated with increased risk of MI. This increased risk appears to be a class effect of these agents, not a specific phenomenon unique to dabigatran or protective effect of warfarin. These findings support the need for enhanced postmarket surveillance of oral DTIs and other novel agents.

Idraparinux or idrabiotaparinux for long-term venous thromboembolism treatment: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Venous thromboembolism (VTE) is a prevalent disease with potential serious consequences. Idraparinux and idrabiotaparinux are two kinds of long-acting pentasaccharides. Evidence has shown that idraparinux and idrabiotaparinux are effective anticoagulants. However, up to now, there is no consensus on whether they are better than other anticoagulation methods for long-term VTE treatment.

OBJECTIVE

To evaluate the effect of idraparinux or idrabiotaparinux versus other anticoagulation methods for long-term VTE treatment.

METHODS

We searched Cochrane Central Register of Controlled Trials, PubMed, Embase, Web of science, clinical trial registry web sites (clinical trials,WHO clinical trial registry), Googlescholar, PubMed related articles and companies' web sites electronically up to Dec 30(th), 2012 and manually searched the reference lists and conference proceedings. Only randomized controlled trial (RCT) involving adult patients comparing idraparinux and/or idrabiotaparinux versus other anticoagulation methods for long-term VTE treatment was included. Two reviewers evaluated the studies and extracted data independently. Pooled risk ratios (RRs) were calculated as outcome measures and Revman 5.2 software was used to analyze data. Our primary efficacy and safety outcomes were the recurrent VTE and major bleeding rates.

RESULTS

We included four RCTs and involved 8584 participants on idraparinux or idrabiotaparinux versus standard warfarin for VTE treatment from 9364 references. We did not perform meta-analysis on the VTE rate because of the significant heterogeneity. We used the fixed effect model to analyze the safety outcomes and demonstrated that idraparinux or idrabiotaparinux decreased major bleeding rate significantly (RR 0.73, 95% CI 0.54 to 0.98, P = 0.04) but had a trend to increase the all cause mortality (RR 1.26, 95% CI 1.00 to 1.57, P = 0.05) compared with warfarin.

CONCLUSIONS

Until now there is not sufficient evidence to clarify whether idraparinux or idrabiotaparinux is as effective and safe as the standard warfarin treatment for VTE treatment.

Cardiovascular outcomes during treatment with dabigatran: comprehensive analysis of individual subject data by treatment

Background

Dabigatran 150 mg twice daily was shown to be superior to warfarin in preventing stroke in subjects with nonvalvular atrial fibrillation (SPAF) in the RE-LY (Randomized Evaluation of Long-term anticoagulation therapY) trial. Numerically, more myocardial infarctions occurred in patients receiving dabigatran compared with well-controlled warfarin. This observation prompted a comprehensive analysis of cardiovascular outcomes, including myocardial infarction, in all completed Phase II and III trials of dabigatran etexilate.

Methods

The analysis included comparisons of dabigatran with warfarin, enoxaparin, and placebo. Data were analyzed for the occurrence of cardiovascular events from 14 comparative trials (n = 42,484) in five different indications. Individual study data were evaluated, as well as pooled subject-level data grouped by comparator.

Results

In the pooled analysis of individual patient data comparing dabigatran with warfarin (SPAF and venous thromboembolism treatment indications), myocardial infarction occurrence favored warfarin (odds ratio [OR] 1.30, 95% confidence interval [CI] 0.96–1.76 for dabigatran 110 mg twice daily and OR 1.42, 95% CI 1.07–1.88 for dabigatran 150 mg twice daily). The clinically relevant composite endpoint of myocardial infarction, total stroke, and vascular death demonstrated numerically fewer events in dabigatran 150 mg patients (OR 0.87, 95% CI 0.77–1.00), but was similar for dabigatran 110 mg (OR 0.99, 95% CI 0.87–1.13). Dabigatran had similar myocardial infarction rates when compared with enoxaparin or placebo.

Conclusion

These analyses suggest a more protective effect of well-controlled warfarin, but not enoxaparin, compared with dabigatran in preventing myocardial infarction in multiple clinical settings. Dabigatran showed an overall positive benefit-risk ratio for multiple clinically important cardiovascular composite endpoints in all evaluated clinical indications. In conclusion, these data suggest that myocardial infarction is not an adverse drug reaction associated with use of dabigatran.

Improving outcomes in patients with atrial fibrillation: rationale and design of the Early treatment of Atrial fibrillation for Stroke prevention Trial

BACKGROUND

Even on optimal therapy including anticoagulation and rate control, major cardiovascular complications (stroke, cardiovascular death, and acute heart failure) are common in patients with atrial fibrillation (AF). Conceptually, maintenance of sinus rhythm could prevent adverse outcomes related to AF. Rhythm control therapy has been only moderately effective in published trials, and its potential benefit was offset by side effects of repeated interventions.

RATIONALE

Rhythm control therapy applied early after the first diagnosis of AF could preserve atrial structure and function and maintain sinus rhythm more effectively than the current practice of delayed rhythm control (when symptoms persist after otherwise effective rate control). Furthermore, catheter ablation and new antiarrhythmic drugs have enhanced the potential effectiveness and safety of rhythm control therapy. The EAST will test whether an early, modern rhythm control therapy can reduce cardiovascular complications in AF.

DESIGN

The EAST (Early treatment of Atrial fibrillation for Stroke prevention Trial) will randomize approximately 3,000 patients with recent onset AF at risk for stroke (CHA₂DS₂VASc score ≥2) to either guideline-mandated usual care or to usual care plus early rhythm control therapy in a prospective, randomized, open, blinded outcome assessment trial. All patients will be followed up until the end of the trial for the composite primary outcome of cardiovascular death, stroke, worsening of heart failure, and myocardial infarction. Nights spent in hospital will be counted as a coprimary outcome. Usual care will consist of anticoagulation, therapy of underlying heart disease, and rate control as an initial approach. Early rhythm control therapy will consist of usual care plus rhythm control therapy by antiarrhythmic drugs, catheter ablation, and a patient-operated electrocardiographic device to monitor the ongoing rhythm. Key secondary outcomes include cognitive function and quality of life.

CONCLUSION

EAST will determine whether rhythm control therapy, when applied early after the initial diagnosis of AF, can prevent cardiovascular complications associated with AF.