Oral anticoagulation, stroke and thromboembolism in patients with atrial fibrillation and valve bioprosthesis

Thromboembolic and bleeding events after valvular intervention in patients with atrial fibrillation

AIM

To assess outcomes after cardiac surgery with biological valve replacement, valve repair or transcatheter aortic valve implantation (TAVI) in patients with atrial fibrillation (AF) in accordance with oral anticoagulant (OAC) treatment.

METHODS

All patients in Sweden undergoing valvular intervention with AF were included. Associations between OAC exposure and cardiovascular (CV) events (composite of CV death, ischaemic stroke or systemic embolism) and major bleeding were investigated using Cox regression analysis. The analysis was separated in time periods of 0-3 and 3-12 months after discharge.

RESULTS

4730 patients were included in the first time period, 54.0% had received a surgical biological valve prosthesis, 23.8% valve repair and 22.2% TAVI. Exposure to warfarin (comparator) was 62.3%, to non-vitamin K antagonist oral anticoagulants (NOACs) 10.0% and to no OAC 27.7%. NOAC exposure was associated with similar risk of the composite CV outcome and major bleeding from 0 to 3 months. No OAC was associated with increased risk of the composite CV outcome (HR 1.71; 95% CI 1.26 to 2.32) and similar risk of major bleeding. Further analysis of the bioprosthetic valve replacement subgroup indicated increased risk of CV death when exposed to NOAC (HR 2.58; 95% CI 1.15 to 5.78) and no OAC (HR 2.82; 95% CI 1.65 to 4.82) compared with warfarin from 0 to 3 months. No differences were seen between 3 and 12 months.

CONCLUSION

In this registry-based cohort study of patients with AF with severe valvular heart disease undergoing various valvular interventions, NOAC appears to be comparable with warfarin regarding efficacy and safety. Patients not receiving OAC had higher risk of CV events. NOAC was associated with increased CV death compared with warfarin in the surgical bioprosthetic valve replacement subgroup, illustrating the importance of being cautious when extrapolating data from one patient group to another. Further studies comparing NOAC and warfarin in the early postoperative phase are warranted, especially following surgical bioprosthetic valve replacement.

An Evidence-Based Approach to Anticoagulation Therapy Comparing Direct Oral Anticoagulants and Vitamin K Antagonists in Patients With Atrial Fibrillation and Bioprosthetic Valves: A Systematic Review, Meta-Analysis, and Network Meta-Analysis

Direct oral anticoagulants (DOACs) are a newer class of anticoagulants that inhibit factor Xa or factor IIa and include drugs such as rivaroxaban, apixaban, edoxaban, betrixaban, and dabigatran. Although vitamin K antagonists (VKAs) have been traditionally used to prevent thromboembolic events, DOACs have gained popularity because of their faster onset and offset of action and reduced need for monitoring. This study aimed to provide more data for anticoagulants in patients with atrial fibrillation with bioprosthetic heart valves by incorporating all available trials to date. A search was performed across 5 electronic databases to identify relevant studies. We analyzed the data using a pooled risk ratio for categorical outcomes and used the I2 test to determine heterogeneity. The quality of randomized controlled trials was assessed using the Cochrane risk of bias assessment tool, and the National Institutes of Health tool was used for observational studies. Our study included a frequentist network meta-analysis (MA) of the aggregate data to obtain the network estimates for the outcomes of interest. We retrieved 28 studies with a total of 74,660 patients with bioprosthetic heart valves. Our MA significantly showed that DOACs decrease the risk of all-cause bleeding (risk ratio [RR] 0.80, 95% confidence interval [CI] 0.75 to 0.85, p >0.00001), stroke and systemic embolization (RR 0.89, 95% CI 0.80 to 0.99, p = 0.03), and intracranial bleeding outcomes (RR 0.62, 95% CI 0.45 to 0.86, p = 0.004) compared with VKA. In contrast, there was no significant difference between the compared groups in major bleeding (RR = 0.92, 95% CI 0.84 to 1.02, p = 0.10) and all-cause mortality outcomes (RR = 0.96, 95% CI 0.85 to 1.07, p = 0.43), respectively. In addition, the network MA results did not favor any of the studied interventions over each other (p <0.05) regarding all-cause bleeding, mortality, stroke and systemic embolization, and major bleeding outcomes. In conclusion, our study found that DOACs are more effective in reducing the risk of bleeding, stroke, systemic embolism, and intracranial bleeding than VKAs. However, no significant difference was observed in the incidence of gastrointestinal bleeding, major bleeding, thromboembolic events, and all-cause mortality. In addition, our network MA did not identify any specific DOAC treatment as more favorable than others.

Effectiveness and safety of non-vitamin K direct oral anticoagulants in atrial fibrillation patients with bioprosthetic valve

Background

Non-vitamin K direct oral anticoagulant (DOAC) is effective for prevention of embolic events in nonvalvular atrial fibrillation (AF) patients. However, the effectiveness and safety of DOAC in AF patients who have bioprosthetic heart valve (BPHV) is largely unknown.

Methods

We retrospectively identified patients with AF and BPHV, using the diagnostic code and medical device and surgery information from the Korean National Health Insurance Service database, between 2013 and 2018. A 1:2 propensity score-matched cohort (n = 724 taking warfarin; n = 362 taking DOAC) was constructed and analyzed for the primary clinical outcome, a composite of ischemic stroke and systemic embolism. Important secondary outcomes included major bleeding, all-cause death, and the net clinical outcome, defined as a composite of all embolic events, major bleeding, and death.

Results

The mean age was 78.9±6.8 years old, and 45% (n = 489) were male. The mean CHA2DS2-VASc score was 4.7±1.4. DOAC was non-inferior to warfarin for preventing ischemic stroke and systemic embolism (hazard ratio [HR] 1.14, 95% confidence interval [CI] 0.56–2.34), major bleeding (HR 0.80, 95% CI 0.32–2.03) and all-cause death (HR 1.09, 95% CI 0.73–1.63). As for the net clinical outcome, DOAC was also similar to warfarin (HR 1.06, 95% CI 0.76–1.47). These outcomes were not different in various subgroups analyzed.

Conclusion

In this nationwide Korean AF population with a BPHV, DOAC was at least as effective and safe as warfarin for the prevention of systemic embolic events. These results suggest that DOAC may be an excellent alternative to warfarin in AF patients with BPHV.

The Characteristics, Long-Term Outcomes, Risk Factors, and Antithrombotic Therapy in Chinese Patients With Atrial Fibrillation and Bioprosthetic Valves

Introduction: There were few data about the clinical profiles and long-term outcomes in Chinese patients with atrial fibrillation (AF) and bioprosthetic valves.

Methods: The retrospective study enrolled 903 patients with bioprosthetic valve replacement at our hospital and discharged with a diagnosis of AF from January 2010 to December 2018.

Results: The median age was 65.6 (61.9–69.1) years, and 548 (60.7%) patients were women. During a follow-up period of 3.84 (2.64–5.51) years, 68 (1.8 per 100 person-years) patients died, 81 (2.1 per 100 person-years) patients developed thromboembolism, and 23 (0.6 per 100 person-years) patients experienced major bleeding. The CHA₂DS₂-VASc score, as a categorical variable (low, moderate, or high risk), predicted the risk of thromboembolism with the C-statistic of 0.6 (95% CI: 0.511–0.689, p = 0.046). The incidence of the CHA₂DS₂-VASc score increment was 11.6 per 100 person-years, and the annual reclassification rate of stroke risk (from a low or moderate group to a higher group) was 12.7%. The current proportion of oral anticoagulants was 52.3, 59, and 63.2%, respectively, in the low, moderate, and high stroke risk groups. Age (OR: 1.04, 95% CI: 1.01–1.06, p = 0.01), left atrial size (OR: 1.05, 95% CI: 1.03–1.08, p < 0.001), and rheumatic heart disease (OR: 1.49, 95% CI: 1.05–2.10, p = 0.025) were positively associated with the use of oral anticoagulants. The history of chronic kidney disease (OR: 0.20, 95% CI: 0.05–0.76, p = 0.018), prior surgical ablation (OR: 0.33, 95% CI: 0.24–0.47, p < 0.001), and antiplatelet agent use (OR: 0.08, 95% CI: 0.05–0.13, p < 0.001) were inversely related to the use of oral anticoagulants. Higher admission estimated glomerular filtration rate (HR: 0.515, 95% CI: 0.311–0.853, p = 0.01), left ventricular ejection fraction (HR: 0.961, 95% CI: 0.931–0.992, p = 0.014), concomitant surgical ablation (HR: 0.348, 95% CI: 0.171–0.711, p = 0.004), and rheumatic heart disease history (HR: 0.515, 95% CI: 0.311–0.853, p = 0.01) were associated with a lower risk of death. Surgical ablation (HR: 0.263, 95% CI: 0.133–0.519, p < 0.001) and oral anticoagulants (HR: 0.587, 95% CI: 0.375–0.918, p = 0.019) were related to a lower risk of thromboembolism.

Conclusion: Chinese patients with AF and bioprosthetic valve(s) were relatively young and had a high prevalence of rheumatic heart disease with few comorbidities. The percentage of mitral bioprosthetic valve replacement was high. The proportion of concomitant surgical ablation or surgical left atrial appendage occlusion or exclusion was relatively low. The thromboembolic events were the major long-term adverse events. The anticoagulation therapy was underused in patients at moderate or high stroke risk. The CHA₂DS₂-VASc score was verified to be used for predicting stroke risk in this population. The stroke risk dynamically changed; it needed to be reestimated once the risk factor changed.

Preoperative paroxysmal atrial fibrillation predicts high cardiovascular mortality in patients undergoing surgical aortic valve replacement with a bioprosthesis: CAREAVR study

Background

Preoperative permanent atrial fibrillation (AF) is associated with impaired outcome after surgical aortic valve replacement (SAVR). The impact of preoperative paroxysmal AF, however, has remained elusive.

Purpose

We assessed the impact of preoperative paroxysmal AF on outcome in patients undergoing SAVR with bioprosthesis.

Methods

A total of 666 patients undergoing isolated AVR with a bioprosthesis were included. Survival data was obtained from the national registry Statistics Finland. Patients were divided into three groups according to the preoperative rhythm: sinus rhythm (n = 502), paroxysmal AF (n = 90), and permanent AF (n = 74).

Results

Patients in the sinus rhythm and paroxysmal AF groups did not differ with respect to age (P = .484), gender (P = .402) or CHA₂DS₂‐VASc score (P = .333). At 12‐month follow‐up, AF was present in 6.2% of sinus rhythm patients and in 42.4% of paroxysmal AF patients (P < .001). During follow‐up, incidence of fatal strokes in the paroxysmal AF group was higher compared to sinus rhythm group (1.9 vs 0.4 per 100 patient‐years, HR 4.4 95% Cl 1.8‐11.0, P = .001). Cardiovascular mortality was higher in the paroxysmal AF group than in the sinus rhythm group (5.0 vs 3.0 per 100 patient‐years, HR 1.70 95% CI 1.05‐2.76, P = .03) and equal to patients in the permanent AF (5.0 per 100 patient‐years).

Conclusion

Patients undergoing SAVR with bioprosthesis and history of paroxysmal AF had higher risk of developing permanent AF, cardiovascular mortality and incidence of fatal strokes compared to patients with preoperative sinus rhythm. Life‐long anticoagulation should be considered in patients with a history of preoperative paroxysmal AF.

Thymosin β4 prevents oxygen-glucose deprivation/reperfusion-induced injury in rat cortical neurons

PURPOSE

This study investigated whether thymosin (T) β4 protects against oxygen-glucose deprivation/reperfusion (OGD/R) injury in rat cortical neurons, as well as the underlying mechanisms.

METHODS

Primary rat cortical neurons were transfected with Tβ4 overexpression plasmid; the transfection efficiency was confirmed by detecting Tβ4 expression by fluorescence quantitative PCR and Western blotting. The OGD/R model was established and apoptotic cells were quantified by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling. Structural changes in the endoplasmic reticulum were visualized by transmission electron microscopy. The expression levels of 78-kDa glucose-regulated protein (GRP) 78, C/EBP-homologous protein (CHOP), B-cell lymphoma (Bcl)-2, and Bcl-2-associated X protein (Bax) were determined by Western blotting. The effect of Tβ4 on OGD/R injury was evaluated by adding exogenous Tβ4 to neuronal cultures.

RESULTS

Cortical neurons were identified by the expression of neuron-specific enolase. In OGD/R cells, the rate of apoptosis was increased and GRP78, CHOP, and Bax were upregulated whereas Bcl-2 was downregulated relative to the control group. These effects were reversed by Tβ4 overexpression. Endoplasmic reticulum (ER) stress was observed in the OGD/R group, but this was abolished in neurons overexpressing Tβ4. The protective effect of Tβ4 against OGD/R injury was also demonstrated in cells treated with exogenous Tβ4 (10 ng/mL), which blocked OGD/R-induced apoptosis by inhibiting ER stress-related and pro-apoptotic protein expression.

CONCLUSION

Tβ4 prevents OGD/R-induced ER stress-dependent apoptosis in cortical neurons, and is a potential treatment for cerebral ischemia-reperfusion injury.

Predicting Thromboembolic and Bleeding Event Risk in Patients with Non-Valvular Atrial Fibrillation: A Systematic Review

BACKGROUND

 Atrial fibrillation (AF) is a common cardiac arrhythmia that increases the risk of stroke. Medical therapy for decreasing stroke risk involves anticoagulation, which may increase bleeding risk for certain patients. In determining the optimal therapy for stroke prevention for patients with AF, clinicians use tools with various clinical, imaging and patient characteristics to weigh stroke risk against therapy-associated bleeding risk.

AIM

 This article reviews published literature and summarizes available risk stratification tools for stroke and bleeding prediction in patients with AF.

METHODS

 We searched for English-language studies in PubMed, Embase and the Cochrane Database of Systematic Reviews published between 1 January 2000 and 14 February 2018. Two reviewers screened citations for studies that examined tools for predicting thromboembolic and bleeding risks in patients with AF. Data regarding study design, patient characteristics, interventions, outcomes, quality, and applicability were extracted.

RESULTS

 Sixty-one studies were relevant to predicting thromboembolic risk and 38 to predicting bleeding risk. Data suggest that CHADS₂, CHA₂DS₂-VASc and the age, biomarkers, and clinical history (ABC) risk scores have the best evidence for predicting thromboembolic risk (moderate strength of evidence for limited prediction ability of each score) and that HAS-BLED has the best evidence for predicting bleeding risk (moderate strength of evidence).

LIMITATIONS

 Studies were heterogeneous in methodology and populations of interest, setting, interventions and outcomes analysed.

CONCLUSION

 CHADS₂, CHA₂DS₂-VASc and ABC scores have the best prediction for stroke events, and HAS-BLED provides the best prediction for bleeding risk. Future studies should define the role of imaging tools and biomarkers in enhancing the accuracy of risk prediction tools.

PRIMARY FUNDING SOURCE

 Patient-Centered Outcomes Research Institute (PROSPERO #CRD42017069999).

Non-vitamin K antagonist oral anticoagulants in atrial fibrillation patients with bioprosthetic valves

INTRODUCTION

The non-vitamin K antagonist oral anticoagulants (NOACs), which include dabigatran, apixaban, edoxaban and rivaroxaban, are preferred over vitamin K antagonists for stoke prevention in most patients with non-valvular atrial fibrillation. The NOACs are contraindicated in atrial fibrillation patients with rheumatic mitral stenosis or mechanical heart valves. There is evidence that bioprosthetic heart valves are less thrombogenic than mechanical heart valves, but it is unknown whether the risk of thromboembolism in atrial fibrillation patients with bioprosthetic valves differs from that in patients without such valves. Areas covered: The authors present a review of the efficacy and safety evidence surrounding the use of NOACs for stroke prevention in atrial fibrillation patients with bioprosthetic heart valves. Expert commentary: While the data is limited, there is no significant difference in thromboembolic, and bleeding outcomes in patients with AF and bioprosthetic heart valves treated with NOAC therapy. Future studies are required before definitive conclusions can be drawn regarding the safety and efficacy of NOAC therapy in AF patients bioprosthetic heart valves.

Stroke prevention in atrial fibrillation: Past, present and future

Concepts and our approaches to stroke prevention in atrial fibrillation (AF) have changed markedly over the last decade. There has been an evolution over the approach to stroke and bleeding risk assessment, as well as new treatment options. An increasing awareness of AF has led to calls to improve the detection of and population screening for AF. Stroke and bleeding risk assessment continues to evolve, and the ongoing debate on balance between simplicity and practicality, against precision medicine will continue. In this review article, we provide an overview of past, present and the (likely) future concepts and approaches to stroke prevention in AF. We propose three simple steps (the Birmingham ‘3-step’) that offers a practical management pathway to help streamline and simplify decision-making for stroke prevention in patients with AF.

Note: The review process for this paper was fully handled by Christian Weber, Editor in Chief.

Evolving cardiovascular uses of direct-acting oral anticoagulants: a paradigm shift on the horizon?

Direct-acting oral anticoagulants (DOACs), by virtue of pharmacological properties perceived as innovative, are changing the therapeutic scenario of patients requiring short- and long-term anticoagulation. The evidence gathered so far (from pre-approval pivotal trials to real-world post-marketing observational data) consistently confirms that DOACs are overall comparable to vitamin-K antagonists (VKAs) in terms of safety, efficacy, effectiveness and unequivocally documents a clinically relevant reduced risk of intracranial bleeding in the settings of non-valvular atrial fibrillation (AF) and venous thromboembolism. The following issues are attracting considerable clinical interest: (a) identifying specific subpopulations of patients with AF most likely to benefit from one of these agents (the so-called tailored therapy), and (b) expanding therapeutic indications in emerging diseases characterized by arterial and venous thromboembolic risk. In these scenarios, the risk-benefit profile of DOACs, as compared to VKAs or heparins, is still incompletely characterized. In cardiology, the challenging task of selecting a suitable or even the most appropriate DOAC for patients with AF and a particular phenotype prompted experts to provide suggestions based on careful review of subgroups of patients from pivotal RCTs. However, in the past few months, variegated multicenter trials have been published (RE-CIRCUIT, PIONEER-AF-PCI, GEMINI-ACS-1), with potential influence on clinical practice. Therefore, this review aims to update the latest evidence on the evolving therapeutic uses of DOACs in the cardiovascular area, addressing potential impact for clinicians.

Non-Vitamin K Oral Anticoagulants for Stroke Prevention in Special Populations with Atrial Fibrillation

Atrial fibrillation (AF) is associated with an increased risk of ischemic stroke or systemic embolism compared with normal sinus rhythm. These strokes may efficiently be prevented in patients with risk factors using oral anticoagulant therapy, with either vitamin K antagonists (VKAs) or non-vitamin K antagonist oral anticoagulants (NOACs) (i.e., direct thrombin inhibitors or direct factor Xa inhibitors). Owing to their specific risk profiles, some AF populations may have increased risks of both thromboembolic and bleeding events. These AF patients may be denied oral anticoagulants, whilst evidence shows that the absolute benefits of oral anticoagulants are greatest in patients at highest risk. NOACs are an alternative to VKAs to prevent stroke in patients with "non-valvular AF", and NOACs may offer a greater net clinical benefit compared with VKAs, particularly in these high-risk patients. Physicians have to learn how to use these drugs optimally in specific settings. We review concrete clinical scenarios for which practical answers are currently proposed for use of NOACs based on available evidence for patients with kidney disease, elderly patients, women, patients with diabetes, patients with low or high body weight, and those with valve disease.

Italian intersociety consensus on DOAC use in internal medicine

The direct oral anticoagulants (DOACs) are drugs used in clinical practice since 2009 for the prevention of stroke or systemic embolism in non-valvular atrial fibrillation, and for the treatment and secondary prevention of venous thromboembolism. The four DOACs, including the three factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) and one direct thrombin inhibitor (dabigatran) provide oral anticoagulation therapy alternatives to Vitamin K antagonists (VKAs). Despite their clear advantages, the DOACs require on the part of the internist a thorough knowledge of their pharmacokinetic and pharmacodynamic characteristics to ensure their correct use, laboratory monitoring and the appropriate management of adverse events. This document represents a consensus paper on the use of DOACs by representatives of three Italian scientific societies: the Italian Society of Internal Medicine (SIMI), the Federation of the Associations of Hospital Managers (FADOI), and the Society for the Study of Haemostasis and Thrombosis (SISET). This document formulates expert opinion guidance for pragmatic managing, monitoring and reversing the anticoagulant effect of DOACs in both chronic and emergency settings. This practical guidance may help the internist to create adequate protocols for patients hospitalized ion internal medicine wards, where patients are often elderly subjects affected by poly-morbidities and renal insufficiency, and, thus, require particular attention to drug-drug interactions and peri-procedural protocols.

Defining nonvalvular atrial fibrillation: A quest for clarification

Non-vitamin K oral anticoagulants (NOACs) are currently recommended for patients with nonvalvular atrial fibrillation since the publication of the 4 major pivotal trials evaluating the efficacy and safety of factor IIa and factor Xa inhibitors. The definition of nonvalvular atrial fibrillation is unclear, varying from one trial to another and even between North American and European guidelines, which is a source of uncertainties in clinical practice. However, many patients with atrial fibrillation present signs of valvular involvement, and clarification of this term is needed to not deny NOACs to patients based on the wrong perception that they may have valvular atrial fibrillation. The currently unique contraindications to NOACs are patients with mechanical heart valves and those with moderate-to-severe mitral stenosis, as stated by the recent 2015 position paper of the European Heart Rhythm Association. Patients with native heart valve involvement, regardless of their severity, are suitable for NOAC therapy. Patients with bioprosthetic heart valves and mitral valve repair may be suitable for NOACs except for the first 3 and the first 3-6 months postoperatively, respectively. Patients with transaortic valve implantation or percutaneous transluminal aortic valvuloplasty are also considered as being eligible for NOACs, although the bleeding risk has to be carefully considered in this population often requiring a combination with antiplatelet therapy. Future studies are warranted to increase the level of evidence of use of NOACs, particularly in patients with transaortic valve implantation and valvular surgery, and to determine whether they could be used in the future in the only 2 remaining contraindications.