Antithrombotic Therapy in Atrial Fibrillation

Is Stroke risk analysis (SRA) a reliable method for predicting atrial fibrillation? A systematic review

INTRODUCTION

Atrial fibrillation is responsible for a considerable number of cases of cardioembolism, accounting for 17% to 30% of the etiologies of all strokes. The software known as Stroke Risk Analysis (SRA) detects patients at high risk of paroxysmal atrial fibrillation by analyzing a continuous electrocardiogram recorded over different periods of time.

OBJECTIVES

This article aims to carry out a systematic review investigating the effectiveness of the SRA method in predicting the risk of stroke patients having paroxysmal atrial fibrillation as the cause of the event.

METHODS

The methods correspond to the format of the International Prospective Register of Systematic Reviews Protocol, according to CRD Identification Code: CRD42021253974. A systematic search was carried out in BMJB, PubMed/MEDLINE, Science Direct and LILACS. Six cohort studies met the inclusion criteria, representing a total of 2,088 participants with stroke, and compared the detection of patients with paroxysmal atrial fibrillation on the continuous recording electrocardiogram with a time variation of 1 to 48h with the use of SRA.

RESULTS

Studies have shown that SRA has a high negative predictive value (between 96 and 99.1%) and can contribute to the selection of patients at high risk of paroxysmal atrial fibrillation to be referred for implantable cardiac monitoring to continue the investigation.

CONCLUSIONS

A sequential combination of SRA with implantable cardiac monitoring is a promising strategy for detecting undiagnosed paroxysmal atrial fibrillation. Thus, the SRA can act as a cost-effective pre-selection tool to identify patients at higher risk of having paroxysmal atrial fibrillation as a possible cause of stroke and who may benefit from implantable cardiac monitoring. However, the lack of randomized studies is a limitation that must be considered.

Potentially inappropriate prescribing in multimorbid and polymedicated older adults with AF: A Systematic Review and Meta-Analysis

AIM

Polypharmacy in multimorbid older patients with atrial fibrillation (AF) is a risk factor for potentially inappropriate prescribing (PIP). We aimed to systematically assess the evidence on the prevalence of PIP and its impact on adverse health outcomes in this patient group.

METHODS

A systematic search of the published peer-reviewed literature describing the prevalence of PIP and/or its association with adverse health outcomes in multimorbid (AF plus one comorbidity) and polymedicated (≥ 2 drugs) adults ≥ 65 years was done up to March 2023. A meta-analysis of the prevalence of PIP of (direct) oral anticoagulants ((D)OACs) was conducted using a random-effects model. Leave-one-out analysis was performed with R (version 4.2.2) and RStudio (version 2022.12.0+353).

RESULTS

Of the 12 studies included, only one reported on the prevalence of overall PIP (65%). The meta-analysis of 10 studies assessing PIP of (D)OACs produced a pooled prevalence [95% confidence interval (CI)] of 35% [30-40%], with significant heterogeneity between the included studies (I2 95%). No statistically significant association was reported in three studies between PIP of (D)OACs, cardiovascular (CV) and all-cause mortality, hospital readmission, CV hospitalisation and stroke. Reported associations between PIP and major bleeding differed, with one study demonstrating a significant association (odds ratio 2.17; 95% CI 1.14-4.12) and the other study not showing such association.

CONCLUSION

This systematic review highlights the scarce evidence regarding the prevalence of PIP and its association with adverse health outcomes in multimorbid older adults with AF. Large, prospective and better-designed studies are needed.

New score for predicting thromboembolic events in patients with atrial fibrillation using direct oral anticoagulants

Determinants of thrombotic events remain uncertain in patients with atrial fibrillation treated with direct oral anticoagulants (DOACs). Our aim was to identify risk factors associated with thromboembolism in patients with at atrial fibrillation on DOACs and to construct and externally validate a predictive model that would provide a validated tool for clinical assessment of thromboembolism. In the development cohort, prediction model was built by logistic regression, the area under the curve (AUC), and Nomogram. External validation and calibration of the model using AUC and Hosmer-Lemeshow test. This national multicenter retrospective study included 3263 patients with atrial fibrillation treated with DOACs. The development cohort consisted of 2390 patients from three centers and the external validation cohort consisted of 873 patients from 13 centers. Multifactorial analysis showed that heavy drinking, hypertension, prior stroke/transient ischemic attack (TIA), cerebral infarction during hospitalization were independent risk factors for thromboembolism. The Alfalfa-TE risk score was constructed using these four factors (AUC = 0.84), and in the external validation cohort, the model showed good discriminatory power (AUC = 0.74) and good calibration (Hosmer-Lemeshow test P value of 0.649). Based on four factors, we derived and externally validated a predictive model for thromboembolism with DOACs in patients with atrial fibrillation (Alfalfa-TE risk score). The model has good predictive value and may be an effective tool to help reduce the occurrence of thromboembolism in patients with DOACs.

Left atrial appendage angiography for stroke risk prediction in patients with atrial fibrillation

BACKGROUND

The current risk stratification schemes for stroke in patients with atrial fibrillation (AF) are insufficient for an accurate assessment of stroke risk.

AIMS

This study evaluates the association between the mechanical function of the left atrial appendage (LAA), as assessed by angiography, and the risk of stroke.

METHODS

We conducted a cross-sectional study to assess the mechanical function of the LAA by measuring the left atrial appendage ejection fraction (LAAEF) and grading the contrast retention (CR) using angiography.

RESULTS

A total of 746 patients referred for a left atrial appendage occlusion (LAAO) procedure with (n=151; stroke group) or without (n=595; control group) a history of stroke were included in the analysis. LAAEF was significantly lower (14% [9-19] vs 20% [12-33]; p<0.001) and grade 3 CR was more common (66.9% vs 33.9%; p<0.001) in patients with a history of stroke. Multivariable analysis showed that CR was independently associated with stroke in patients with AF (grade 2 vs grade 1=7.29; 95% confidence interval [CI]: 2.84-21.65; p<0.001; grade 3 vs grade 1=16.45; 95% CI: 6.16-51.02; p<0.001). The receiver operating characteristics curve demonstrated that CR identified patients with stroke more accurately than the CHA2D-VASc score (C-statistic 0.712 vs 0.512; p<0.001), and the combination of CR and the CHA2DS2-VASc score provided the best performance (C-statistic 0.871 vs 0.829 [CHA2DS2-VASc score alone]; p=0.048) Conclusions: Impaired mechanical function of the LAA, indicated by a low LAAEF and CR, is associated with a history of stroke in patients with AF. Assessment of CR using LAA angiography helps improve the stratification scheme for stroke risk prediction.

Studies on Atrial Fibrillation and Venous Thromboembolism in the Past 20 Years: A Bibliometric Analysis Via CiteSpace and VOSviewer

The conjunction of atrial fibrillation (AF) and venous thromboembolism (VTE) is common in clinical practice. Over the last 2 decades, a significant number of articles (2500) have been published about AF and VTE. To effectively analyze and present these vast amounts of information, this study uses bibliometric research methods to categorize and consolidate these publications. The number of publications has increased yearly, especially since 2012. The United States was the most prolific country, with 1054 studies published. The most productive institution was McMaster University. Gregory Y.H. Lip was the most prolific author. The keyword analysis identified that the research focuses from 2003 to 2014 were factor Xa inhibitor, dabigatran etexilate, direct thrombin inhibitor, double-blind, deep vein thrombosis, molecular weight heparin, stroke prevention, etc. From 2015 to 2016, research mainly focused on venous thromboembolism, antithrombotic therapy, anticoagulant, warfarin, atrial fibrillation, stroke, and pulmonary embolism. Studies during 2017 to 2022 focused on apixaban, direct oral anticoagulant, rivaroxaban, dabigatran, hemorrhage, edoxaban, medicine efficacy and safety, risk factors, clinical management, and vitamin K antagonists. Since 2018, novel oral anticoagulants have been the most commonly used keywords. On the whole, most studies of AF and VTE focus on pathogenesis and therapeutic drugs. The causal relationship between AF and VTE, the effectiveness and safety of novel oral anticoagulants in the treatments, the anticoagulant regimen of AF and VTE co-disease, and the treatment regimen for vulnerable populations such as the elderly or obese people were the focus of current research and will continue to be the central point of future research.

Characteristics, Thrombus Resolution, and Long-Term Outcomes in Patients with Nonvalvular Atrial Fibrillation and Atrial Thrombus

To assess the prevalence and management of atrial thrombus in patients with nonvalvular atrial fibrillation (NVAF) and identify the risk factors of the nonresolution of atrial thrombus. This single-center retrospective observational study consecutively enrolled patients with NVAF and atrial thrombus detected using transesophageal echocardiography (TEE) or cardiac computed tomography angiography (CTA) from January 2012 to December 2020. Patients with prior left atrial appendage (LAA) intervention were excluded. The primary endpoint was the presence of atrial thrombus, while the secondary endpoint was the complete resolution of atrial thrombus. The prevalence of atrial thrombus in patients with NVAF was 1.4%. Ninety patients with atrial thrombus (mean age 62.8 ± 11.9 years and 61.1% men) were finally analyzed. Atrial thrombus was in the LAA in 82 (91.1%) patients. During follow up, 60% of the patients showed complete resolution of atrial thrombus. Congestive heart failure (odds ratio [OR]: 8.94; 95% confidence interval [CI]: 1.67-47.80) and a history of ischemic stroke (OR: 8.28; 95% CI: 1.48-46.42) were independently associated with the risk of the nonresolution of atrial thrombus. The presence of atrial thrombus in patients with NVAF who received anticoagulation therapy is non-negligible. Even in anticoagulated patients, TEE or cardiac CTA might still be needed. Congestive heart failure and a history of ischemic stroke are risk factors of the nonresolution of atrial thrombus.

Interplay between cardiovascular and thyroid dysfunctions: A review of clinical implications and management strategies

Cardiovascular diseases (CVD) and thyroid dysfunction are two of the most prevailing disorders in the world that are closely interlinked. Actions of thyroid hormones are mediated via thyroid receptors present in the myocardium and the vascular tissue. Primary mechanism that links thyroid dysfunction with CVD is the modification of cardiovascular risk factors (dyslipidemia, blood pressure, coagulation parameters, etc.) resulting in endothelial and left ventricular systolic and diastolic dysfunction.

Both overt and subclinical hyperthyroidism and hypothyroidism may cause adverse alterations in cardiac function. Hyperthyroidism gives rise to palpitation, atrial fibrillation, systolic hypertension, and heart failure, whereas hypothyroidism increases diastolic hypertension, pericardial effusion, and the risk of ischemic heart disease via altering lipid and coagulation parameters. Early recognition and treatment of thyroid dysfunction may prevent adverse cardiovascular events in patients with or without pre-existing CVD.

Certain cardiac conditions and medications can cause alterations in thyroid function that may predispose an individual to higher morbidity and mortality. In certain situations, thyroid dysfunction treatment may have cardiovascular benefits. This study deals with the interplay between cardiovascular and thyroid dysfunctions associated with clinical implications and management strategies.

Left atrial appendage occlusion in recurrent ischaemic stroke, a multicentre experience

BACKGROUND

Oral anticoagulation therapy (OAC) remains the gold standard for ischaemic stroke prevention in patients with non-valvular atrial fibrillation (NVAF) and elevated stroke risk. Percutaneous left atrial appendage occlusion (LAAO) has emerged as a potential alternative for stroke prevention in patients who cannot tolerate OAC. Although no randomized data is available, recurrent stroke in NVAF-patients, while on adequate OAC, is regarded as a treatment failure and therefore is considered as a potential indication for LAAO, based upon expert opinion.

METHODS/OBJECTIVES

A multicentre retrospective cohort study evaluating efficacy, safety and mortality of LAAO in NVAF-patients presenting with recurrent ischaemic stroke, after excluding other plausible causes.

RESULTS

Fifteen LAAO have been performed in NVAF-patients with recurrent stroke despite ongoing OAC, after exclusion of other plausible causes. Mean age was 78.1 ± 5.8 years, mean CHA₂DS₂-VASc-score = 6 ± 1.2 and mean HAS-BLED-score = 5 ± 1.2. Successful implantation was achieved in all patients (73% Amplatzer device and 27% Watchman device), without any access-related complications and only one procedure/device-related complication (device embolization) was reported. In all but four patients, OAC was continued at long term after LAAO. No haemorrhagic strokes and only two ischaemic strokes were observed. During follow-up three patients died, all due to non-atrial fibrillation or non-device-related causes.

CONCLUSIONS

In NVAF-patients at high risk for stroke presenting with recurrent stroke despite adequate OAC, LAAO may be considered an adjunctive, but not alternative treatment to OAC with high feasibility and safety.

Abbreviations: AF: atrial fibrillation; ESC: European Society of Cardiology; INR: international normalized ratio; LAA: left atrial appendage; LAAO: left atrial appendage occlusion; NOAC: non-vitamin K oral anticoagulants; NVAF: non-valvular atrial fibrillation; OAC: oral anticoagulation; RS: recurrent (ischaemic) stroke; SD: standard deviation; TIA: transient ischaemic attack; TOE: transoesophageal echocardiography; TTE: transthoracic echocardiography; VKA: vitamin K antagonists.

The risk and timing of acute ischemic stroke after electrical cardioversion for atrial fibrillation in Taiwan: A nationwide population-based cohort study

BACKGROUND

There is a positive association between electrical cardioversion (ECV) and acute ischemic stroke (AIS). Although 4 weeks of anticoagulation therapy after ECV in atrial fibrillation (AF) patients is generally suggested by current guidelines to reduce the risk of AIS, limited studies have been conducted in Asian populations to determine the risk and timing of AIS after ECV for AF in recent years. Therefore, we aim to use the National Health Insurance Research Database (NHIRD) in Taiwan to determine the risk and timing of AIS after ECV for AF.

METHODS

The data analyzed in this nationwide population-based retrospective cohort study were obtained from the NHIRD in Taiwan. The outcome in this study was the cumulative incidence of AIS in patients with AF during 7-day and 30-day follow-up periods after the patients underwent ECV.

RESULTS

Our analysis included 39,697 patients with AF, of whom 5723 received ECV and 5723 were propensity score-matched controls. Compared to the controls, patients who received ECV exhibited a significantly increased incidence of 7-day AIS development (adjusted hazard ratio [HR] = 1.524, p = 0.003). In contrast, the incidence of 30-day AIS development showed no significant increase (adjusted HR = 1.301, p = 0.426).

CONCLUSIONS

AF patients who underwent ECV had a higher incidence of 7-day AIS development but not 30-day AIS development. Considering the timing of AIS development after ECV in AF patients, the optimal duration of antithrombotic therapy after ECV deserves further investigation.

The Intriguing Relationships of von Willebrand Factor, ADAMTS13 and Cardiac Disease

von Willebrand factor (VWF) is an adhesive protein involved in primary hemostasis and facilitates platelet adhesion to sites of vascular injury, thereby promoting thrombus formation. VWF exists in plasma as multimers of increasing size, with the largest (high molecular weight; HMW) expressing the greatest functional activity. A deficiency of VWF is associated with a bleeding disorder called von Willebrand disease (VWD), whereas an excess of VWF, in particular the HMW forms, is associated with thrombosis. ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif-13), also known as VWF-cleaving protease, functions to moderate the activity of VWF by cleaving multimers of VWF and limiting the expression of the largest multimers of VWF. A deficiency of ADAMTS13 is therefore associated with an excess of (HMW forms of) VWF, and thus thrombosis. Indeed, any disturbance of the VWF/ADAMTS13 ratio or ‘axis’ may be associated with pathophysiological processes, including prothrombotic tendency. However, both thrombosis or bleeding may be associated with such disturbances, depending on the presenting events. This review evaluates the relationship of VWF and ADAMTS13 with cardiac disease, including cardiac failure, and associated pathophysiology.

Extensive thrombosis after COVID-19 vaccine: cause or coincidence?

A 62-year-old Caucasian female patient presented with abdominal pain, vomiting and fever 1 day after administration of COVID-19 vaccine. Bloodwork revealed anaemia and thrombocytosis. Abdominal CT angiography showed a mural thrombus at the emergence of the coeliac trunk, hepatic and splenic arteries, and extensive thrombosis of the superior and inferior mesenteric veins, splenic and portal veins, and the inferior vena cava, extending to the left common iliac vein. The spleen displayed extensive areas of infarction. Aetiological investigation included assessment of congenital coagulation disorders and acquired causes with no relevant findings. Administration of COVID-19 vaccine was considered a possible cause of the extensive multifocal thrombosis. After reviewing relevant literature, it was considered that other causes of this event should be further investigated. Thrombosis associated with COVID-19 vaccine is rare and an aetiological relationship should only be considered in the appropriate context and after investigation of other, more frequent, causes.

EACVI recommendations on cardiovascular imaging for the detection of embolic sources: endorsed by the Canadian Society of Echocardiography

Cardioaortic embolism to the brain accounts for approximately 15-30% of ischaemic strokes and is often referred to as 'cardioembolic stroke'. One-quarter of patients have more than one cardiac source of embolism and 15% have significant cerebrovascular atherosclerosis. After a careful work-up, up to 30% of ischaemic strokes remain 'cryptogenic', recently redefined as 'embolic strokes of undetermined source'. The diagnosis of cardioembolic stroke remains difficult because a potential cardiac source of embolism does not establish the stroke mechanism. The role of cardiac imaging-transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE), cardiac computed tomography (CT), and magnetic resonance imaging (MRI)-in the diagnosis of potential cardiac sources of embolism, and for therapeutic guidance, is reviewed in these recommendations. Contrast TTE/TOE is highly accurate for detecting left atrial appendage thrombosis in patients with atrial fibrillation, valvular and prosthesis vegetations and thrombosis, aortic arch atheroma, patent foramen ovale, atrial septal defect, and intracardiac tumours. Both CT and MRI are highly accurate for detecting cavity thrombosis, intracardiac tumours, and valvular prosthesis thrombosis. Thus, CT and cardiac magnetic resonance should be considered in addition to TTE and TOE in the detection of a cardiac source of embolism. We propose a diagnostic algorithm where vascular imaging and contrast TTE/TOE are considered the first-line tool in the search for a cardiac source of embolism. CT and MRI are considered as alternative and complementary tools, and their indications are described on a case-by-case approach.

Coronary Embolism despite CHA₂DS₂-VASc Score of Zero: Should We Reconsider Anticoagulation?

Coronary embolism (CE) is a rare but important cause of acute coronary syndrome. The most common source of emboli is considered to be infective endocarditis and atrial fibrillation. Various studies have estimated the prevalence of coronary embolism; however, diagnosis is challenging. Often, it is difficult to differentiate. Nonetheless, this is an important step as treating the underlying cause of an embolism is essential to limit recurrence. However, while this condition may have fatal consequences, due to its uncommon occurrence, there is no consensus on diagnosis and management. We present a case of a 53-year-old obese male, with a history of paroxysmal atrial fibrillation not on anticoagulation due to a low CHA₂DS₂-VASc score, who presented with chest pain associated with lightheadedness. ECG on admission revealed coarse atrial fibrillation, and troponin was gradually elevating on serial lab workup. Coronary angiography revealed a distal left anterior descending artery occlusion with apical wall akinesis without any evidence of atherosclerotic coronary artery disease. A presumptive diagnosis of coronary embolism secondary to paroxysmal atrial fibrillation was made, and the patient was started on anticoagulation despite a low CHA₂DS₂-VASc score. This case not only highlights coronary embolism but also illustrates that a low CHA₂DS₂-VASc score does not mean there is no risk of emboli. For such patients, it is important to take clinical reasoning into account along with the CHA₂DS₂-VASc score to determine the benefit of anticoagulation.

Valvular and Nonvalvular Atrial Fibrillation in Patients Undergoing Transcatheter Aortic Valve Replacement

OBJECTIVES

The aim of this study was to investigate the impact of valvular and nonvalvular atrial fibrillation (AF) in patients undergoing transcatheter aortic valve replacement (TAVR).

BACKGROUND

AF has been associated with adverse clinical outcomes after TAVR. However, the differential impact of valvular as opposed to nonvalvular AF has not been investigated.

METHODS

In a retrospective analysis of a prospective registry, valvular AF was defined as AF in the setting of concomitant mitral stenosis or the presence of a mitral valve prosthesis. The presence of mitral stenosis was determined by pre-procedural echocardiography. The primary endpoint was a composite of cardiovascular death or disabling stroke at 1 year after TAVR.

RESULTS

Among 1,472 patients undergoing TAVR between August 2007 and June 2018, AF was recorded in 465 patients (31.6%) and categorized as nonvalvular in 376 (25.5%) and valvular in 89 (6.0%). AF scores including HAS-BLED, CHADS₂, and CHA₂DS₂-VASc were comparable between patients with nonvalvular and valvular AF. The primary endpoint occurred in 9.3% of patients with no AF, in 14.5% of patients with nonvalvular AF (hazard ratio: 1.57; 95% confidence interval: 1.12 to 2.20; p = 0.009), and in 24.2% of patients with valvular AF (hazard ratio: 2.75; 95% confidence interval: 1.71 to 4.41; p < 0.001). Valvular AF conferred an increased risk for cardiovascular death or disabling stroke compared with nonvalvular AF (hazard ratio: 1.77; 95% confidence interval: 1.07 to 2.94; p = 0.027).

CONCLUSIONS

The presence of valvular AF in patients undergoing TAVR increased the risk for cardiovascular death or disabling stroke compared with both no AF and nonvalvular AF. (SWISS TAVI Registry; NCT01368250).

Uncovering the Potential Differentially Expressed miRNAs and mRNAs in Ischemic Stroke Based on Integrated Analysis in the Gene Expression Omnibus Database

INTRODUCTION

Ischemic stroke is the third leading cause of death. There is no known treatment or cure for the disease. Moreover, the pathological mechanism of ischemic stroke remains unclear.

OBJECTIVE

We aimed to identify potential microRNAs (miRNAs) and mRNAs, contributing to understanding the pathology of ischemic stroke.

METHODS

First, the data of miRNA and mRNA were downloaded for differential expression analysis. Then, the regulatory network between miRNA and mRNAs was constructed. Third, top 100 differentially expressed mRNAs were used to construct a protein-protein interaction network followed by the function annotation of mRNAs. In addition, in vitro experiment was used to validate the expression of mRNAs. Last, receiver operating characteristic diagnostic analysis of differentially methylated genes was performed.

RESULTS

Totally, up to 26 differentially expressed miRNAs and 1,345 differentially expressed mRNAs were identified. Several regulatory interaction pairs between miRNA and mRNAs were identified, such as hsa-miR-206-HMGCR/PICALM, hsa-miR-4491-TMEM97, hsa-miR-3622b-5p/hsa-miR-548k-KLF12, and hsa-miR-302a-3p/hsa-miR-3145-3p-CTSS. MAPK signaling pathway (involved DUSP1) and the Notch signaling pathway (involved NUMB and CREBBP) were identified. The expression validation of KLF12, ARG1, ITGAM, SIRT4, SERPINH1, and DUSP1 was consistent with the bioinformatics analysis. Interestingly, hsa-miR-206, hsa-miR-4491, hsa-miR-3622b-5p, hsa-miR-548k, hsa-miR-302a-3p, hsa-miR-3145-3p, KLF12, and ID3 had the potential diagnostic value of ischemic stroke.

CONCLUSIONS

The identified differentially expressed miRNAs and mRNAs may be associated with the development of ischemic stroke.

Diagnosis and Treatment for embolic stroke of undetermined source: Consensus statement from the Taiwan stroke society and Taiwan society of cardiology

Cryptogenic stroke comprises about one-quarter of ischemic strokes with high recurrence rate; however, studies specifically investigating the features and treatment of this stroke subtype are rare. The concept of 'embolic stroke of undetermined source' (ESUS) may facilitate the development of a standardized approach to diagnose cryptogenic stroke and improve clinical trials. Since recent large randomized control trials failed to demonstrate a reduction in stroke recurrence with anticoagulants, anti-platelet agents remain the first-line treatment for ESUS patients. Nevertheless, patients with high risk of stroke recurrence (e.g., those with repeated embolic infarcts despite aspirin treatment) require a more extensive survey of stroke etiology, including cardiac imaging and prolonged cardiac rhythm monitoring. Anticoagulant treatments may still benefit some subgroups of high-risk ESUS patients, such as those with multiple infarcts at different arterial territories without aortic atheroma, the elderly, or patients with high CHA₂D₂-VASc or HOVAC scores, atrial cardiopathy or patent foramen ovale. Several important ESUS clinical trials are ongoing, and the results are anticipated. With rapid progress in our understanding of ESUS pathophysiology, new subcategorizations of ESUS and assignment of optimal treatments for each ESUS subgroup are expected in the near future.

Shared decision making for thromboembolic prophylaxis in non-valvular atrial fibrillation: promise and problems with the American College of Cardiology's AnticoagEvaluator (based on SPARCtool)

BACKGROUND AND METHODS

People with atrial fibrillation face an increased risk of thromboembolic events, and deciding on an antithromboembolic strategy in non-valvular atrial fibrillation is a prime opportunity for shared decision making. Therefore, tools facilitating this process are highly desirable. The American College of Cardiology strives for such with its 'AnticoagEvaluator', which is based on Peter Loewen's 'SPARCtool'. However, it appears these tools were released without standard peer review. Therefore, an analysis of these tools was undertaken to evaluate their soundness, namely proper use of baseline risk and effect estimates from the available evidence.

RESULTS

Despite Loewen's laudable idea and the American College of Cardiology developing AnticoagEvaluator based on Loewen's work, both tools have a flaw: they use relative effect estimates based on composite outcomes (thromboembolic and haemorrhagic) that do not match the baseline risk to which they are applied (thromboembolic). This can lead to importantly inaccurate impressions of therapeutic efficacy. This analysis explores this issue and offers potential solutions.

CONCLUSIONS

The American College of Cardiology releasing and promoting a tool that gives misleading impressions of therapeutic efficacy is of considerable importance, though SPARCtool should also be corrected as a matter of importance. Means to correct the tools are identified herein, and if corrected, these tools stand to better fulfil their intended purpose as important and useful additions for clinical and shared decision making. This article's analysis of the tools has a directly practical purpose, but it also serves as an instructive example of key elements of evidence-based medicine and shared decision making.

Detection and quantification of warfarin in pharmaceutical dosage form and in spiked human plasma using surface enhanced Raman scattering

Analytical approaches for the quantitation of warfarin in plasma are high in demand. In this study, a novel surface enhanced Raman scattering (SERS) technique for the quantification of the widely used anticoagulant warfarin sodium in pharmaceutical dosage form and in spiked human plasma was developed. The colloidal-based SERS measurements were carefully optimized considering the laser wavelength, the type of metal nanoparticles, their surface functionalization and concentration as well as the time required for warfarin to associate with the metal surface. Poly(diallyldimethylammonium chloride) coated silver nanoparticles (PDDA-AgNPs) were established as a substrate which greatly enhanced the weak warfarin Raman signal with high reproducibility. The limit of detection was calculated in both water and human plasma to be 0.56 nM (0.17 ngmL^-1) and 0.25 nM (0.08 ngmL^-1) respectively, with a high degree of accuracy and reproducibility. The proposed method is simple, economical, and easily applied for routine application requiring only small plasma samples and also could be potentially useful for pharmacokinetic research on warfarin.

Restarting Therapeutic Anticoagulation After Elective Craniotomy for Patients with Chronic Atrial Fibrillation: A Review of the Literature

The decision to restart systemic anticoagulation after surgery requires a nuanced risk-benefit analysis. The potential for surgical site bleeding must be balanced against the risk of thromboembolic events. In the context of postoperative neurosurgical patients, the consequences of either hemorrhage or thromboembolism can be devastating. However, few studies to date have attempted to determine the optimal time to resume anticoagulation after craniotomy. As a result, the decision of when to restart anticoagulation remains largely subjective and highly variable between surgeons and institutions. In this study, we aim to develop an algorithm that incorporates existing metrics and expert opinion toward the goal of developing guidelines for restarting anticoagulation after elective craniotomy.

Significant cardiac disease complicating Graves' disease in previously healthy young adults

SUMMARY

Graves' disease is associated with tachydysrythmia, cardiac ischaemia and cardiomyopathy - all uncommon in young adults without previous cardiac disease. We present three young individuals who developed cardiac complications after periods of uncontrolled Graves' disease. Subject 1: A 34-year-old female had severe thyrotoxic symptoms for weeks. Investigations showed fT4: 98.4 (11-25 pmol/L), fT3: 46.9 (3.1-6.8 pmol/L), TSH <0.01 (0.27-4.2 mU/L) and thyrotrophin receptor antibody (TRAb): 34.8 (<0.9 U//l). She had appropriate treatment but several weeks later she became breathless despite improving thyroid function. Echocardiography showed a pericardial effusion of 2.9 cm. She responded well to steroids and NSAIDs but developed active severe Graves' orbitopathy after early total thyroidectomy. Subject 2: A 28-year-old male developed thyrotoxic symptoms (fT4: 38 pmol/L, fT3: 13.9 pmol/L, TSH <0.01 (for over 6 months) and TRAb: 9.3 U/L). One month after starting carbimazole, he developed acute heart failure (HF) due to severe dilated cardiomyopathy - EF 10-15%. He partially recovered after treatment - EF 28% and had early radioiodine treatment. Subject 3: A 42-year-old woman who had been thyrotoxic for several months (fT4: 54.3; fT3 >46.1; TSH <0.01; TRAb: 4.5) developed atrial fibrillation (AF) and heart failure. Echocardiography showed cardiomegaly - EF 29%. She maintains sinus rhythm following early total thyroidectomy (EF 50%). Significant cardiac complications may occur in previously fit young adults, who have had uncontrolled Graves' disease for weeks to months. Cardiac function recovers in the majority, but early definitive treatment should be discussed to avoid Graves' disease relapse and further cardiac decompensation.

LEARNING POINTS

Cardiac complications of Graves' disease are uncommon in young adults without previous cardiac disease. These complications may however occur if Graves' disease had been poorly controlled for several weeks or months prior to presentation. Persistent symptoms after adequate control should alert clinicians to the possibility of cardiac disease. Specific treatment of Graves' disease and appropriate cardiac intervention results in complete recovery in the majority and carries a good prognosis. Early definitive treatment should be offered to them to prevent cardiac decompensation at times of further relapse.

Prevalence and Prognostic Implications of Valve Disease in Patients With Atrial Fibrillation Initiating Direct Oral Anticoagulants

INTRODUCTION AND OBJECTIVES

Valvular heart disease in patients with atrial fibrillation included in clinical trials with direct oral anticoagulants (DOAC) is common and is associated with worse prognosis. The aim of this study was to evaluate the prevalence of valvular heart disease and its influence on clinical events in real-world clinical practice.

METHODS

We conducted a retrospective multicenter registry including 2297 consecutive patients with nonvalvular atrial fibrillation initiating DOAC between January 2013 and December 2016. Valvular heart disease was defined as moderate or severe involvement. The primary study endopoint was the composite of death, stroke or transient ischemic attack/systemic embolism or major bleeding. A competing risks analysis was carried out using a Fine and Gray regression model, with death being the competing event.

RESULTS

A total of 499 (21.7%) patients had significant valvular heart disease. The most common form was mitral regurgitation (13.7%). Patients with valvular heart disease were older and had more comorbidities. After multivariable analysis, valvular heart disease was associated with a higher risk for the primary endpoint (HR, 1.54; 95%CI, 1.22-1.94; P<.001), death (HR, 1.44; 95%CI, 1.09-1.91, P=.010), and major bleeding (HR, 1.85; 95%CI, 1.23-2.79, P=.003), but there was no association with thromboembolic events (P >.05).

CONCLUSIONS

In patients with nonvalvular atrial fibrillation initiating DOACs, valvular heart disease is common and increases the risk of mortality, stroke, transient ischemic attack/systemic embolism, and major bleeding complications. These findings confirm the results of clinical trials and expand them to a real-life clinical setting.

Cost-effectiveness of apixaban for stroke prevention in non-valvular atrial fibrillation in Saudi Arabia

BACKGROUND

Apixaban, an oral anticoagulant for stroke and systemic embolism prevention in non-valvular atrial fibrillation (NVAF), was superior to warfarin in prevention of stroke and systemic embolism, bleeding outcomes and mortality (ARISTOTLE trial), and substantially reduced stroke risk, with no significant increase in major or intracranial bleeding risk versus aspirin (AVERROES trial).

OBJECTIVE

Estimate cost-effectiveness of apixaban versus other anticoagulants for NVAF treatment in Saudi Arabia.

DESIGN

Lifetime Markov model.

SETTING

A published model was adapted from the United Kingdom (UK) to the Saudi Arabia setting.

PATIENTS AND METHODS

The model enabled pairwise comparisons of apixaban against other anticoagulants, aspirin, and aspirin+clopidogrel. Apart from warfarin and aspirin, comparisons were indirect. Subpopulations included vitamin K antagonist (VKA) suitable and unsuitable patients. Medication and physician visit costs were from published lists. A cost ratio (0.533), from comparison of UK and Saudi physician visit costs, was applied to UK model inputs to estimate local event costs. Background life expectancy was from Saudi life tables. Model structure, treatment comparators, patient characteristics, event rates, and utilities were unchanged. Costs and health benefits were discounted by 3.5% annually.

MAIN OUTCOME MEASURE

Incremental cost-effectiveness ratio of cost per quality-adjusted life-year (QALY) gained.

SAMPLE SIZE

Model cohort of 1000 NVAF patients, for VKA suitable and VKA unsuitable populations.

RESULTS

Apixaban was dominant versus warfarin (VKA suitable) and rivaroxaban (VKA suitable and unsuitable). Compared against dabigatran (110mg, 150 mg, 110/150mg), the cost/QALY gained for apixaban was $5166, $11 143, $10 849 (VKA suitable) and $5 157, $14 424, $14 134 (VKA unsuitable), respectively. Cost/QALY for apixaban versus aspirin and aspirin+clopidogrel was $14 805 and $5784 (VKA suitable); and $10 564 and $4203 (VKA unsuitable), respectively. Sensitivity analyses demonstrated consistency of findings across varying inputs.

CONCLUSIONS

Apixaban was found to be cost-effective for stroke prevention among Saudi NVAF patients, when assessed using a US$20 000 willingness-to-pay threshold.

LIMITATIONS

Lack of robust local clinical, cost and utility data for model inputs. Lack of head-to-head clinical trial data for rivaroxaban, dabigatran, and clopidogrel plus aspirin comparators.

CONFLICT OF INTEREST

Study was funded by Pfizer Inc. and Bristol Myers-Squibb. KO, RS, SAK and AAA received salaries from their respective employers, but did not receive direct financial compensation for participation in or authorship of this study.

Do Restoring and Maintaining Sinus Rhythm Have a Beneficial Effect on Secondary Prevention of Stroke in Patients With Atrial Fibrillation? A Pilot Study

We aimed to determine whether attempts to restore and maintain sinus rhythm will reduce recurrent stroke in patients with atrial fibrillation (AF). Patients (n = 245) between March 1998 and May 2002 with AF who had an ischemic stroke including transient ischemic attack 1 to 12 months before transesophageal echocardiographic examination and had been followed for 3 years were retrospectively reviewed. Cardioversion was attempted in 130 patients; 117 (90%) patients were successfully cardioverted (rhythm control group). The 13 patients who could not be cardioverted and 115 patients who did not undergo cardioversion were assigned to the rate control group. Age, gender, ischemic heart disease, hypertension, diabetes mellitus, congestive heart failure, mitral valve disease, and left atrial diameter were similar in both groups. The rhythm control group included 56 patients (48.7%) who were still in sinus rhythm after 3 years. During follow-up, there were 2 embolic events (3.4%) and 2 deaths (3.4%) in the rhythm control group, whereas 18 embolic events (14.6%) and 18 deaths (14.6%) occurred in the rate control group (P = .049 and P = .049, respectively). Restoration and maintenance of sinus rhythm seems to have a beneficial effect on secondary prevention of stroke in patients with AF.

Association Between Time-in-Therapeutic Tacrolimus Range and Early Rejection After Heart Transplant

BACKGROUND

Historically, there is perceived pressure to achieve therapeutic levels of tacrolimus quickly after heart transplant (HT). We evaluated the association between time within therapeutic tacrolimus range and time to therapeutic trough and rejection in the 30 days following HT.

METHODS

This is a single-center retrospective cohort study of consecutive adult HT patients receiving immunosuppression. Goal trough tacrolimus levels were 10-15 ng/ml. Surveillance endomyocardial biopsies were performed weekly for 4 weeks. Outcomes included the effect of time to and time-in-therapeutic tacrolimus range (Rosendaal method) on 30-day clinical rejection, 1R/1B, and 2R or higher histologic occurrences.

RESULTS

We reviewed 67 HT patients (median age 58.8 yrs). For clinical rejection versus no-rejection groups, the median (25th, 75th percentile) time to therapeutic tacrolimus levels was 9.5 (8, 12.3) days versus 9.0 (7, 13) days (p=0.623). The median time-in-therapeutic tacrolimus range was 34.1% (23.2, 42.2) versus 36.2% (19.9, 51.2), respectively (p=0.512). Similarly, we observed no significant differences in time to and time-in-therapeutic tacrolimus range in patients who developed grade 1R/1B (p=0.650 and p=0.725) or grade 2R or higher histology (p=0.632 and p=0.933).

CONCLUSIONS

Our small single-center analysis suggests that neither time to nor time in therapeutic tacrolimus range predicted acute rejection within 30 days of HT.

Identifying risk factor for development of perioperative venous thromboembolism in patients with gastrointestinal malignancy

BACKGROUND

Current data suggests that decreasing VTE incidence may require focus on other factors. This study aimed to identify perioperative risk factors for VTE in patients undergoing surgery for gastrointestinal (GI) malignancy.

METHODS

Patients undergoing surgery for GI malignancy from 2013 to 2016 were grouped according to whether or not they developed a postoperative VTE, and groups were compared along demographic, perioperative, and outcome variables.

RESULTS

Patients who developed VTE were more likely to be older (67 ± 11 VTE vs. 61 ± 10 no VTE, p = 0.04), male (92% vs. 59%, p = 0.02), and have a history of atrial fibrillation (39% vs. 11%, p = 0.01). They also experienced higher intraoperative blood loss (328 ± 724 mL no VTE vs. 918 ± 1885 mL VTE, p = 0.01). On multivariable analysis, history of atrial fibrillation was independently associated with development of postoperative VTE (odds ratio = 3.83, 95% confidence interval = 1.13-13.05, p = 0.03).

CONCLUSION

A prior history of atrial fibrillation independently predicts increased risk of developing VTE after surgery for GI malignancy. Improving understanding of the underlying VTE pathophysiology in these patients can help guide effective prevention strategies.

Dental management of patients on anti-thrombotic agents

The number of geriatric patients seeking dental service is ever-rising because of increased life expectancy, also with problem of increased chronic medical conditions. One of them are patients on anti-thrombotic medication. Bleeding complication after minor oral surgery by anti-thrombotic agents is of concerns to dentists on dental management of these patients. Risk and benefit of the anti-thrombotic agents must be weighed before initiating dental procedures, which should be established as a treatment guideline. Purpose of the paper is to optimize the management of the dental patients on anti-thrombotic medication via standardization of treatment protocol of such a patient.

Clinically relevant bleeding in cancer patients treated for venous thromboembolism from the CATCH study

Essentials Cancer patients receiving anticoagulants for venous thromboembolism have an elevated bleeding risk. This secondary analysis of CATCH assessed characteristics of clinically relevant bleeding (CRB). CRB occurs in 15% of cancer patients with thrombosis using therapeutic doses of anticoagulation. After multivariate analysis, risk factors for CRB were age >75 years and intracranial malignancy.

SUMMARY

Background Cancer patients with acute venous thromboembolism (VTE) receiving anticoagulant treatment have an increased bleeding risk. Objectives We performed a prespecified secondary analysis of the randomized, open-label, Phase III CATCH trial (NCT01130025) to assess the rate and sites of and the risk factors for clinically relevant bleeding (CRB). Patients/Methods Patients with active cancer and acute, symptomatic VTE received either tinzaparin 175 IU kg-1 once daily or warfarin (target International Normalized Ratio [INR] of 2.0-3.0) for 6 months. Fisher's exact test was used to screen prespecified clinical risk factors; those identified as being significantly associated with an increased risk of CRB then underwent competing risk regression analysis of time to first CRB. Results Among 900 randomized patients, 138 (15.3%) had 180 CRB events. CRB occurred in 60 patients (81 events) in the tinzaparin group and in 78 patients (99 events) in the warfarin group (hazard ratio [HR] 0.64; 95% confidence interval [CI] 0.45-0.89). Common bleeding sites were gastrointestinal (36.7%; n = 66), genitourinary (22.8%; n = 41), and nasal (10.0%; n = 18). In multivariate analysis, the risk of CRB increased with age > 75 years (HR 1.83, 95% CI 1.14-2.94) and intracranial malignancy (HR 1.97, 95% CI 1.07-3.62). In the warfarin group, 40.4% of CRB events occurred in patients with with an INR of < 3.0. A lower time in therapeutic range was associated with a higher risk of CRB. Conclusions CRB is a frequent complication in cancer patients with VTE during anticoagulant treatment, and is associated with age > 75 years and intracranial malignancy.

The effectiveness of culturally tailored video narratives on medication understanding and use self-efficacy among stroke patients: A randomized controlled trial study protocol

INTRODUCTION

A substantial number of the world's population appears to end with moderate to severe long-term disability after stroke. Persistent uncontrolled stroke risk factor leads to unpredicted recurrent stroke event. The increasing prevalence of stroke across ages in Malaysia has led to the adaptation of medication therapy adherence clinic (MTAC) framework. The stroke care unit has limited patient education resources especially for patients with medication understanding and use self-efficacy. Nevertheless, only a handful of studies have probed into the effectiveness of video narrative at stroke care centers.

METHOD

This is a behavioral randomized controlled trial of patient education intervention with video narratives for patients with stroke lacking medication understanding and use self-efficacy. The study will recruit up to 200 eligible stroke patients at the neurology tertiary outpatient clinic, whereby they will be requested to return for follow-up approximately 3 months once for up to 12 months. Consenting patients will be randomized to either standard patient education care or intervention with video narratives. The researchers will ensure control of potential confounding factors, as well as unbiased treatment review with prescribed medications only obtained onsite.

RESULTS

The primary analysis outcomes will reflect the variances in medication understanding and use self-efficacy scores, as well as the associated factors, such as retention of knowledge, belief and perception changes, whereas stroke risk factor control, for example, self-monitoring and quality of life, will be the secondary outcomes.

DISCUSSION AND CONCLUSION

The study should be able to determine if video narrative can induce a positive behavioral change towards stroke risk factor control via enhanced medication understanding and use self-efficacy. This intervention is innovative as it combines health belief, motivation, and role model concept to trigger self-efficacy in maintaining healthy behaviors and better disease management.

TRIAL REGISTRATION

ACTRN (12618000174280).

Atrial Fibrillation Recurrence and Peri-Procedural Complication Rates in nMARQ vs. Conventional Ablation Techniques: A Systematic Review and Meta-Analysis

Background and Objectives: Atrial fibrillation is a common abnormal cardiac rhythm caused by disorganized electrical impulses. AF which is refractory to antiarrhythmic management is often treated with catheter ablation. Recently a novel ablation system (nMARQ) was introduced for PV isolation. However, there has not been a systematic review of its efficacy or safety compared to traditional ablation techniques. Therefore, we conducted this meta-analysis on the nMARQ ablation system.

Methods: PubMed and EMBASE were searched up until 1st of September 2017 for articles on nMARQ. A total of 136 studies were found, and after screening, 12 studies were included in this meta-analysis.

Results: Our meta-analysis shows that the use of nMARQ was associated with higher odds of AF non-recurrence (n = 1123, odds ratio = 6.79, 95% confidence interval 4.01–11.50; P < 0.05; I² took a value of 83%). Moreover, the recurrence rate of AF using nMARQ was not significantly different from that of traditional ablation procedures (n = 158 vs. 196; OR = 0.97, 95% confidence interval:0.59–1.61). No significant difference in complication rates was observed between these groups (RR: 0.86; 95% CI: 0.37–1.99; P > 0.05). There were four reported mortalities in the nMARQ group compared to none in the conventional ablation group (relative risk: 1.58; 95% CI: 0.09–29.24; P > 0.05).

Conclusions: AF recurrence rates are comparable between nMARQ and conventional ablation techniques. Although general complication rates are similar for both groups, the higher mortality with nMARQ suggests that conventional techniques should be used for resistant AF until improved safety profiles of nMARQ can be demonstrated.

Propolis ethanolic extracts reduce adenosine diphosphate induced platelet aggregation determined on whole blood

BACKGROUND

Propolis is a well-known bee product containing more than 2000 identified compounds. It has many beneficial effects on human health that include antibacterial, antiviral, anticancer and hepatoprotective justifying its use as a dietary supplement. Platelet aggregation plays crucial role in thrombus formation that can cause stroke or heart attacks. As cardiovascular diseases, including those caused by thrombus formation, are related to 50% of deaths of Western population, the objective of this study was to determine antiaggregatory activity of propolis on platelet aggregation on the whole blood samples.

METHODS

Twenty one propolis samples from Southeast Europe were characterized by spectrophotometric methods to determine content of the total flavonoids and phenolic acids. High performance liquid chromatography coupled with diode array detection was used to identify and quantify individual polyphenols. Platelet aggregation was tested by impedance aggregometry on the whole blood samples of ten healthy volunteers.

RESULTS

The mean content of total polyphenols was 136.14 mg/g and ranged from 59.23 to 277.39 mg/g. Content of total flavonoids ranged between 6.83 and 55.44 mg/g with the mean value of 19.28 mg/g. Percentage of total phenolic acids was in the range 8.79 to 45.67% (mean 26.63%). Minimal antiaggregatory concentration, representing the lowest concentration of propolis extract sample that can cause statistically significant reduction of aggregation, ranged from 5 μM to 10.4 mM. Samples of propolis with lower content of luteolin and higher content of pinocembrin-7-methyleter showed better antiplatelet activity i.e. lower values of minimal antiaggregatory concentration.

CONCLUSIONS

This is the first study that shows antiaggregatory potential of propolis ethanolic extracts on the whole blood samples in the low micromolar concentrations suggesting that propolis supplementation may influence platelet aggregation and consequently thrombus formation. Further in vivo studies are needed to confirm the beneficial effects in prevention of cardiovascular diseases.

Effects of warfarin on biological processes other than haemostasis: A review

Warfarin is the world's most widely used anticoagulant drug. Its anticoagulant activity is based on the inhibition of the vitamin K-dependent (VKD) step in the complete synthesis of a number of blood coagulation factors that are required for normal blood coagulation. Warfarin also affects synthesis of VKD proteins not related to haemostasis including those involved in bone growth and vascular calcification. Antithrombotic activity of warfarin is considered responsible for some aspects of its anti-tumour activity of warfarin. Some aspects of activities against tumours seem not to be related to haemostasis and included effects of warfarin on non-haemostatic VKD proteins as well as those not related to VKD proteins. Inflammatory/immunomodulatory effects of warfarin indicate much broader potential of action of this drug both in physiological and pathological processes. This review provides an overview of the published data dealing with the effects of warfarin on biological processes other than haemostasis.

Oral anticoagulation use by patients with atrial fibrillation in Germany

Atrial fibrillation (AF) is the most common significant cardiac rhythm disorder. Oral anticoagulation (OAC) is recommended by guidelines in the presence of a moderate to high risk of stroke. Based on an analysis of claims-based data, the aim of this contribution is to quantify the stroke-risk dependent OAC utilisation profile of German AF patients as well as the possible causes and the associated clinical outcomes of OAC under-use. Our data set was derived from two large mandatory German medical insurance funds. Risk stratification of patients was based on the CHADS2-score and the CHA2DS2-VASc-score. Two different scenarios were constructed to deal with factors potentially disfavouring OAC use. Causes of OAC under-use and its clinical consequences were analysed using multivariate analysis. Observation year was 2008. A total of 183,448 AF patients met the inclusion criteria. This represents an AF prevalence of 2.21%. The average CHADS2-score was 2.8 (CHA2DS2-VASc-score: 4.3). On between 40.5 and 48.7% of the observed patient-days, there was no antithrombotic protection by OAC, other anticoagulants or aspirin. Older female patients with a high number of comorbidities had a higher risk of OAC under-use. Patients who had already experienced a thromboembolic event had a lower risk of OAC under-use. In the observation year, 3,367 patients experienced a stroke (incidence rate 1.8%). In our multi-level Poisson random effects estimate, OAC use decreases the stroke rate by almost 80% (IRR 0.236). In conclusion, OAC under-use is widespread in the German market. It is associated with severe clinical consequences.

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

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

Venous and arterial thrombosis – pathogenesis and the rationale for anticoagulation

Thromboembolic disorders are major causes of morbidity and mortality. It is well-recognised that the pathogenesis is different for arterial and venous thrombosis; however, both involve coagulation activation. Anticoagulants are used for the prevention and treatment of a wide variety of thromboembolic and related conditions. Agents with anti-inflammatory properties in addition to anticoagulation may be particularly beneficial. Traditional anticoagulants, although effective, are associated with certain limitations. Understanding the pathological processes associated with thrombosis and the rational target for anticoagulation is essential, not only for the development of safer and more effective agents, but also for better clinical management of patients who require anticoagulation therapy. In recent years, new oral agents that target single enzymes of the coagulation cascade have been developed – some of those are in advanced stages of clinical development. Based on scientific rationale, both factor Xa and thrombin are viable targets for effective anticoagulation.

Pharmacokinetics and pharmacodynamics of tecarfarin, a novel vitamin K antagonist oral anticoagulant

Tecarfarin is a vitamin K antagonist (VKA) with reduced propensity for drug interactions. To evaluate the pharmacokinetic (PK), pharmacodynamic (PD), and safety of tecarfarin, we performed single ascending dose (SAD) (n=66), multiple ascending dose (MAD) (n=43), and tecarfarin versus warfarin (n=28) studies in human volunteers. In the SAD, tecarfarin was administered to 5 of 6 subjects (1 received placebo) in each of 11 cohorts. AUC0-∞ exhibited linearity and dose proportionality. Elimination T1/2 ranged from 87–136 hours (h) across all doses. In the MAD, tecarfarin was administered to 5 of 6 volunteers in each of 7 cohorts. The starting dose was continued until the subject’s INR reached the target range (TR) of 1.7 to 2.0. Dosing was down-titrated if the TR was achieved. Elimination T1/2 ranged from 107–140 h. Doses <10 mg had insignificant effect on INR. Higher doses raised INRs and required down-titration to maintain the TR. Steady state INR dosing was 10–20 mg. INR declined promptly after discontinuation. In the comparative study, subjects received tecarfarin or warfarin and dose titrated to a TR of 1.5–2.0. Mean dose after TR was achieved was 13.9 mg (range 10.0–25.5 mg) for tecarfarin and 5.3 mg (range 2.5–9.0 mg) for warfarin. At similar INR levels, the concentration of coagulation factors II, VII, IX, and X were similar for tecarfarin and warfarin. Tecarfarin was tolerated well without serious adverse events in all three studies.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Validation of the CHADS2 clinical prediction rule to predict ischaemic stroke

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

The perioperative management of new direct oral anticoagulants: a question without answers

New direct oral anticoagulant agents (DOAC) are currently licensed for thromboprophylaxis after hip and knee arthroplasty and for longterm prevention of thromboembolic events in non-valvular atrial fibrillation as well as treatment and secondary prophylaxis of venous thromboembolism. Some other medical indications are emerging. Thus, anaesthesiologists are increasingly likely to encounter patients on these drugs who need elective or emergency surgery. Due to the lack of experience and data, the management of DOAC in the perioperative period is controversial. In this article, we review available information and recommendations regarding the periprocedural management of the currently most clinically developed DOAC, apixaban, dabigatran, and rivaroxaban. We discuss two trends of managing patients on DOAC for elective surgery. The first is stopping the DOAC 1–5 days before surgery (depending on the drug, patient and bleeding risk) without bridging. The second is stopping the DOAC 5 days preoperatively and bridging with low-molecular-weight heparin. The management of patients on DOAC needing emergency surgery is also reviewed. As no data exist for the use of haemostatic products for the reversal of the anticoagulant effect in these cases, rescue treatment recommendations are proposed.

Stroke risks and patterns of warfarin therapy among atrial fibrillation patients post radiofrequency ablation: A real-world experience

We assessed the thromboembolic risks of atrial fibrillation (AF) patients who had undergone radiofrequency ablation (RFA) using the CHADS2-VASc risk scoring system and further investigated the patterns of warfarin use for thromboprophylaxis according to patient thromboembolic risk scores.In this study, we analyzed the stroke risks of patients who had undergone RFA for AF at our hospital between March 2014 and June 2016 using the CHADS2, CHADS2-VASc, and Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly (> 65 years) (HAS-BLED) scoring systems. We retrieved medications, co-morbidities, and initial warfarin dosage data. The primary outcome was the percentage of patients initiated with warfarin therapy for stroke prophylaxis in AF who had a CHADS2-VASc score of 0.Totally, 309 patients were initiated with warfarin therapy for stroke prophylaxis in AF post-RFA. The baseline warfarin dosage was 2.76 ± 0.61 mg. The baseline CHADS2-VASC score was 2.93 ± 1.96 and 40 (12.95%) had a CHADS2-VASC score of 0, 42 (13.6%) had a CHADS2-VASCscore of 1, and 227 (73.5%) had a CHADS2-VASC score ≥2. The baseline CHADS2 score was 2.17 ± 1.55 and 48 (15.5%) had a CHADS2 score of 0, 68 (22.0%) had a CHADS2 score of 1, and 193 (62.5%) had a CHADS2 score ≥2. The baseline HAS-BLED score was 1.25 ± 0.91 and 69 (22.3%) had a HAS-BLED score of 0, 121 (39.2%) had a HAS-BLED score of 1, and 119 (38.5%) had a HAS-BLED score ≥2. Patients aged <65 years or 65 years, male and female patients, patients with or without hypertension, coronary heart disease, or diabetes mellitus, and patients with or without previous stroke/transient ischemic attack differed significantly in stroke risks by CHADS2-VASC, CHADS2, and HAS-BLED scores for stroke risks. Patients with different baseline international normalized ratio differed significantly in CHADS2-VASC scores. Furthermore, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and statins were of statistical significance for stroke risks.The majority of AF patients post-RFAs was of high stroke risk and received warfarin thromboprophylaxis in accordance with national guidelines. Our findings suggest that low and intermediate stroke risk patients should be evaluated for stroke risks and risk factors so that tailored warfarin thromboprophylaxis therapy can be given and inappropriate use of warfarin in AF patients can be avoided.

Value of Combining Left Atrial Diameter and Amino-terminal Pro-brain Natriuretic Peptide to the CHA2DS2-VASc Score for Predicting Stroke and Death in Patients with Sick Sinus Syndrome after Pacemaker Implantation

Background:

The CHA2DS2-VASc score is used clinically for stroke risk stratification in patients with atrial fibrillation (AF). We sought to investigate whether the CHA2DS2-VASc score predicts stroke and death in Chinese patients with sick sinus syndrome (SSS) after pacemaker implantation and to evaluate whether the predictive power of the CHA2DS2-VASc score could be improved by combining it with left atrial diameter (LAD) and amino-terminal pro-brain natriuretic peptide (NT-proBNP).

Methods:

A total of 481 consecutive patients with SSS who underwent pacemaker implantation from January 2004 to December 2014 in our department were included. The CHA2DS2-VASc scores were retrospectively calculated according to the hospital medical records before pacemaker implantation. The outcome data (stroke and death) were collected by pacemaker follow-up visits and telephonic follow-up until December 31, 2015.

Results:

During 2151 person-years of follow-up, 46 patients (9.6%) suffered stroke and 52 (10.8%) died. The CHA2DS2-VASc score showed a significant association with the development of stroke (hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.20–1.75, P < 0.001) and death (HR 1.45, 95% CI 1.22–1.71, P < 0.001). The combination of increased LAD and the CHA2DS2-VASc score improved the predictive power for stroke (C-stat 0.69, 95% CI 0.61–0.77 vs. C-stat 0.66, 95% CI 0.57–0.74, P = 0.013), and the combination of increased NT-proBNP and the CHA2DS2-VASc score improved the predictive power for death (C-stat 0.70, 95% CI 0.64–0.77 vs. C-stat 0.67, 95% CI 0.60–-0.75, P = 0.023).

Conclusions:

CHA2DS2-VASc score is valuable for predicting stroke and death risk in patients with SSS after pacemaker implantation. The addition of LAD and NT-proBNP to the CHA2DS2-VASc score improved its predictive power for stroke and death, respectively, in this patient cohort. Future prospective studies are warranted to validate the benefit of adding LAD and NT-proBNP to the CHA2DS2-VASc score for predicting stroke and death risk in non-AF populations.

Atrial fibrillation and hyperthyroidism: A literature review

Atrial fibrillation is the most common arrhythmia worldwide with increasing frequency noted with age. Hyperthyroidism is a well-known cause of atrial fibrillation with a 16%–60% prevalence of atrial fibrillation in patients with known hyperthyroidism Ross et al. (2016). While hyperthyroidism as a causative factor of atrial fibrillation is well established, this literature review aims to answer several questions on this topic including:

1. The relationship of atrial fibrillation to hyperthyroidism

2. Atrial fibrillation as a predictor of hyperthyroidism

3. The pathophysiology of thyrotoxic atrial fibrillation

4. Subclinical hyperthyroidism and the relationship with atrial fibrillation

5. Cardioversion and Catheter ablation of hyperthyroid patients with atrial fibrillation

6. Thrombotic risk of hyperthyroid patients with atrial fibrillation

7. Management of Thyrotoxic Atrial fibrillation

8. Pharmacological rhythm control in patients with hyperthyroidism and atrial fibrillation

9. Treatment of Hyperthyroidism to prevent atrial fibrillation

10. Clinical Implications of Hyperthyroidism and Atrial Fibrillation

e-Health-based management of patients receiving oral anticoagulation therapy: results from the observational thrombEVAL study

Essentials e-Health based health care by an expert centre may advance management of oral anticoagulation. Outcome of patients was compared between an e-health based coagulation service and regular care. Patients in the coagulation service cohort experienced a significantly better clinical outcome. Lower risk for adverse events was related to anticoagulation-specific and non-specific outcome.

SUMMARY

Background Management of oral anticoagulation (OAC) therapy is essential to minimize adverse events in patients receiving vitamin K-antagonists (VKAs). Data on the effect of e-health-based anticoagulation management systems on the clinical outcome of OAC patients are limited. Objectives To compare the clinical outcome of OAC patients managed by an e-health-based coagulation service (CS) with that of patients receiving regular medical care (RMC). Methods The prospective multicenter cohort study thrombEVAL (NCT01809015) comprised 1558 individuals receiving RMC and 760 individuals managed by a CS. Independent study monitoring and adjudication of endpoints by an independent review panel were implemented. Results The primary study endpoint (composite of thromboembolism, clinically relevant bleeding and death) occurred in 15.7 per 100 patient-years (py) with RMC and in 7.0 per 100 py with the CS (rate ratio [RR], 2.3; 95% confidence interval [CI], 1.7-3.1). Rates for major and clinically relevant bleeding were higher with RMC than with the CS: 6.8 vs. 2.6 and 10.1 vs. 3.6 per 100 py, respectively. Thromboembolic events showed an RR of 1.5 (95% CI, 0.8-2.6) comparing RMC with the CS. Hospitalization (RR, 2.6; 95% CI, 2.3-3.0) and all-cause mortality (RR, 4.6; 95% CI, 2.8-7.7) were markedly more frequent with RMC. In Cox regression analysis with adjustment for age, sex, cardiovascular risk factors, comorbidities, treatment characteristics and sociodemographic status, hazard ratios (HR) for the primary endpoint (HR, 2.2; 95% CI, 1.5-3.4), clinically relevant bleeding (HR, 3.1; 95% CI, 1.7-5.5), hospitalization (HR, 2.2; 95% CI, 1.8-2.8) and all-cause mortality (HR, 5.6; 95% CI, 2.9-11.0) favored CS treatment. Conclusions In this study, e-health-based management of OAC therapy was associated with a lower frequency of OAC-specific and non-specific adverse events.

Healthcare utilization and costs for patients initiating Dabigatran or Warfarin

Background

Novel oral anticoagulants (NOAC) such as dabigatran, when compared to warfarin, have been shown to potentially reduce the risk of stroke in patients with non-valvular atrial fibrillation (NVAF) together with lower healthcare resource utilization (HCRU) and similar total costs. This study expands on previous work by comparing HCRU and costs for patients newly diagnosed with NVAF and newly initiated on dabigatran or warfarin, and is the first study specifically in a Medicare population.

Methods

A retrospective matched-cohort study was conducted using data from administrative health care claims during the study period 01/01/2010–12/31/2012. Cox regression analyses were used to compare all-cause risk of first hospitalizations and emergency room (ER) visits. Medical, pharmacy, and total costs per-patient-per-month (PPPM) were compared between dabigatran and warfarin users.

Results

A total of 1110 patients initiated on dabigatran were propensity score-matched with corresponding patients initiated on warfarin. The mean number of hospitalizations (0.92 vs. 1.13, P = 0.012), ER visits (1.32 vs. 1.56, P < 0.01), office visits (21.43 vs. 29.41; P < 0.01), and outpatient visits (10.86 vs. 22.02; P < 0.01) were lower among dabigatran compared to warfarin users. Patients initiated on dabigatran had significantly lower risk of first all-cause ER visits [hazard ratio (HR): 0.84, 95% confidence interval (CI): 0.73–0.98] compared to those initiated on warfarin. Adjusted mean pharmacy costs PPPM were significantly greater for dabigatran users ($510 vs. $250, P < 0.001); however, mean medical costs PPPM ($1912 vs. $1956, P = 0.55) and mean total costs PPPM ($2381 vs. $2183, P = 0.10) were not significantly different compared to warfarin users.

Conclusions

Dabigatran users had significantly lower HCRU compared to warfarin users. In addition, dabigatran users had lower risk of all-cause ER visits. Despite higher pharmacy costs, the two cohorts did not differ significantly in medical or total all-cause costs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-017-0705-x) contains supplementary material, which is available to authorized users.

Anticoagulation Bridge Therapy in Patients with Atrial Fibrillation: Recent Updates Providing a Rebalance of Risk and Benefit

In 2011 we reviewed clinical updates and controversies surrounding anticoagulation bridge therapy in patients with atrial fibrillation (AF). Since then, options for oral anticoagulation have expanded with the addition of four direct oral anticoagulant (DOAC) agents available in the United States. Nonetheless, vitamin K antagonist (VKA) therapy continues to be the treatment of choice for patients who are poor candidates for a DOAC and for whom bridge therapy remains a therapeutic dilemma. This literature review identifies evidence and guideline and consensus statements from the last 5 years to provide updated recommendations and insight into bridge therapy for patients using a VKA for AF. Since our last review, at least four major international guidelines have been updated plus a new consensus document addressing bridge therapy was released. Prospective trials and one randomized controlled trial have provided guidance for perioperative bridge therapy. The clinical trial data showed that bridging with heparin is associated with a significant bleeding risk compared with not bridging; furthermore, data suggested that actual perioperative thromboembolic risk may be lower than previously estimated. Notably, patients at high risk for stroke have not been adequately represented. These findings highlight the importance of assessing thrombosis and bleeding risk before making bridging decisions. Thrombosis and bleeding risk tools have emerged to facilitate this assessment and have been incorporated into guideline recommendations. Results from ongoing trials are expected to provide more guidance on safe and effective perioperative management approaches for patients at high risk for stroke.

Thoracoscopic Ablation With Appendage Ligation Versus Medical Therapy for Stroke Prevention: A Proof-of-Concept Randomized Trial

OBJECTIVE

Atrial fibrillation (AF) has a demonstrable effect on quality of life (QOL). Recurrent stroke occurs in 10% of patients with AF. The objective of this study was to demonstrate proof of concept that thoracoscopic pulmonary vein isolation and atrial appendage ligation (TPVIAL) could prevent recurrent stroke and could potentially improve QOL in patients with AF with a previous stroke.

METHODS

The study was a National Institutes of Health-funded single-center proof-of-concept design that randomized 23 patients with AF-related stroke to TPVIAL (n = 12) or to medical management (n = 11). Quality of life was the primary outcome variable; secondary end points included restoration of rhythm, recurrent stroke, and surgical morbidity.

RESULTS

Quality-of-life subscores at 3 and 6 months revealed improvements in energy and decreases in fatigue in the TPVIAL arm [baseline, 33 (19.8); 3 months, 49.5 (20.6), P = 0.01; 6 months, 55.5 (14.4), P = 0.03]. At 12-month follow-up, there were no recurrent strokes in the TPVIAL group. In the medically treated arm, two patients at 6 months (P = 0.22) and three total patients at 12 months (P = 0.09) had recurrent ischemic stroke. There was one death in the medical management arm. In the TPVIAL arm, no AF recurrence occurred in patients with paroxysmal AF, and one patient had recurrence of persistent and long-standing AF. Seven patients in the TPVIAL arm discontinued warfarin therapy for secondary stroke prevention.

CONCLUSIONS

This small proof-of-concept study showed that TPVIAL improved QOL on two subscores and restored normal sinus rhythm in all but one patient, and it showed the potential to prevent secondary stroke. A larger study will be needed.