Stroke prevention in atrial fibrillation

Risk of Stroke With Mitral Stenosis: The Underlying Mechanism, Treatment, and Prevention

Mitral stenosis (MS), a valvular heart disease, is defined by the narrowing of the mitral valve orifice. The common risk factors for stroke include mitral annular calcification (MAC), diabetes mellitus (DM), male gender, hypertension (HTN), hyperlipidemia, and obesity. Endothelial damage, hypercoagulability, and blood stasis in the left atrium promote the development of the thrombus. Among all the risk factors described, MAC is the independent predictor of stroke. The complicated mechanisms responsible for thromboembolism, predisposing factors for thromboembolism, the risk of cerebrovascular accident (CVA) in MS patients, advanced standardized assessment models for identifying those at risk for stroke, and the possible advantages and disadvantages of available therapies have all been discussed in this review article. We have also discussed newer oral anticoagulants (NOACs) like dabigatran, edoxaban, apixaban, and rivaroxaban. Non-pharmacological therapies are also highlighted such as left atrial appendage ligation and occlusion devices. We also conducted a thorough review of the literature on the efficacy and safety of various NOACs in reducing the risk of stroke.

Speckle tracking analysis: a new tool for left atrial function analysis in systemic hypertension: an overview

Speckle tracking echocardiography (STE) is an imaging technique applied to the analysis of left atrial function. STE provides a non-Doppler, angle-independent and objective quantification of left atrial myocardial deformation. Data regarding feasibility, accuracy and clinical applications of left atrial strain are rapidly gathering. This review describes the fundamental concepts of left atrial STE, illustrates its pathophysiological background and discusses its emerging role in systemic arterial hypertension.

Non-valvular atrial fibrillation: potential clinical implications of the heterogeneous definitions used in trials on new oral anticoagulants

AIMS

To evaluate the potential impact of the different definitions of non-valvular atrial fibrillation reported in the literature and to analyse the possible implications for eligibility for novel oral anticoagulants (NOACs) in clinical practice.

METHODS

We derived the definitions of 'non-valvular atrial fibrillation' from the exclusion criteria of the trials on NOACs, and then assessed the number and percentage of patients fulfilling the various definitions in a cohort of 500 consecutive atrial fibrillation patients, undergoing clinical and echocardiographic evaluation in our cardiology department, as either in-patients or out-patients.

RESULTS

Among the 500 atrial fibrillation patients (mean age 71.2 ± 12.6 years), with permanent atrial fibrillation in 45.2% of the cases, hypertension was very common, either as the main diagnosis or as an associated disease. Valvular heart disease as the main diagnosis (including valvular prosthesis) accounted for 22.8% of the cases. At the echocardiographic evaluation, valvular alterations were very common, especially mitral regurgitation (present, with a variable degree of severity in 63.6% of the cases). Application of the RE-LY exclusion criteria with regard to valvular disease resulted in 116 (23.2%) patients of our cohort classified as valvular atrial fibrillation. This percentage was reduced to 12.2 and 8.8% if ROCKET-AF and ARISTOTLE/ENGAGE-AF criteria, respectively, were applied.

CONCLUSIONS

Non-valvular atrial fibrillation is a common clinical entity, but without a unified definition in the literature. The impact in daily practice of the different definitions adopted in trials is noteworthy, since in one patient out of seven, the eligibility for NOACs can be questioned, simply as a consequence of adopting a more or less restrictive definition.

Novel nonpharmacologic approaches for stroke prevention in atrial fibrillation: results from clinical trials

Atrial fibrillation (AF), the most common cardiac arrhythmia, confers a 5-fold risk of stroke that increases to 17-fold when associated with mitral stenosis. At this time, the most effective long-term solution to protect patients from stroke and thromboembolism is oral anticoagulation, either with vitamin K antagonists (VKAs) or a novel oral anticoagulant (NOAC). Despite the significant benefits they confer, both VKAs and NOACs are underused because of their increased potential for bleeding, and VKAs are underused because of their narrow therapeutic range, need for regular international normalized ratio checks, and interactions with food or medications. In patients with nonvalvular AF, approximately 90% of strokes originate from the left atrial appendage (LAA); in patients with rheumatic mitral valve disease, many patients (60%) have strokes that originate from the left atrium itself. Surgical LAA amputation or closure, although widely used to reduce stroke risk in association with cardiac surgery, is not currently performed as a stand-alone operation for stroke risk reduction because of its invasiveness. Percutaneous LAA closure, as an alternative to anticoagulation, has been increasingly used during the last decade in an effort to reduce stroke risk in nonvalvular AF. Several devices have been introduced during this time, of which one has demonstrated noninferiority compared with warfarin in a randomized controlled trial. This review describes the available technologies for percutaneous LAA closure, as well as a summary of the published trials concerning their safety and efficacy in reducing stroke risk in AF.

Is bleeding a necessary evil? The inherent risk of antithrombotic pharmacotherapy used for stroke prevention in atrial fibrillation

Current European atrial fibrillation (AF) guidelines have assigned a strong recommendation for the initiation of antithrombotic therapy to prevent thromboembolism in all but those AF patients at low risk (or with contraindications). Furthermore, the selection of antithrombotic therapy is based on the absolute risks of thromboembolism and bleeding, and the relative risk and benefit for a given patient. By their very mechanism of action, antithrombotic agents used for stroke prevention in AF will potentially increase the risk of bleeding events. Moreover, the introduction of novel oral anticoagulation agents have introduced new, hitherto ill-defined, deficiencies in the authors' knowledge with respect to anticoagulation monitoring, availability of direct antidotes, drug-drug interactions and the ability to appropriately control and reverse their actions if bleeding events occur. The authors present a comprehensive review on all aspects of bleeding related to currently licensed antithrombotic agents used for stroke prevention in patients with AF.

Prevalence of stroke and the need for thromboprophylaxis in young patients with atrial fibrillation: a cohort study

Atrial fibrillation is the most common cardiac arrhythmia, and age is a well-established independent risk factor for stroke in these patients. Whereas high-risk patients clearly benefit from anticoagulation to prevent stroke, less is known about how to treat low-risk patients. Despite the recent guidelines and studies demonstrating no benefit and excess bleeding risk with aspirin, many low-risk patients still receive this medication. Our objective was to determine the stroke rate in young patients with atrial fibrillation, a group of previously unstudied and predominantly low-risk patients. We hypothesized that the event rate would be so low as to preclude benefit from antithrombotic medications. A retrospective chart review identified patients with atrial fibrillation between the age of 18 and 35. Exclusion criteria included no ECG documentation of atrial fibrillation, anticoagulation, except around the time of cardioversion, and surgical valve disease. The primary outcome was stroke during the period of observation. The final cohort included 99 patients, mean age 27.6 years, followed for a mean of 4.3 years. Mean CHADS2 and CHA2DS2-VASc scores were 0.26 and 0.4, respectively. A total of 42.4% were taking aspirin for over 50% of the time. There was one event identified, a transient ischemic attack in a man not on aspirin with CHADS2 and CHADS2-VASc scores of 1, resulting in event rates of 0.234 per 100 patient-years overall or 0.392 among those not on aspirin. Patients with nonvalvular atrial fibrillation under age 35 have an exceedingly low stroke risk. We assert that aspirin may be unnecessary for most patients in this population, especially those with a CHA2DS2-VASc score of 0.

Oral anticoagulants to reduce the risk of stroke in atrial fibrillation: how should a clinician choose?

Atrial fibrillation (AF), a common arrhythmia that occurs with increasing frequency in the aging population, is associated with increased mortality and morbidity. To ensure that patients receive adequate anticoagulant prophylaxis, clinical guidelines for anticoagulation advocate use of validated scoring systems to stratify patients by cardiovascular risk and predict the individual patient's risk of adverse effects of therapy. Recently approved oral anticoagulants-a direct thrombin inhibitor and the factor Xa inhibitors-may offer advantages over the 50-year standard, warfarin, for efficacy, safety, and ease of administration. Clinical trial experience with the newly approved agents and others, yet to be approved, will define their relative value in reducing the risk of thromboembolism associated with AF. This article discusses issues that may help clinicians choose among these newer agents and individualize treatment appropriately.

A review of the clinical utility of INR to monitor and guide administration of prothrombin complex concentrate to orally anticoagulated patients

Background and objectives

The number of patients treated with oral anticoagulation (OAC) is increasing and these patients are monitored by International Normalized Ratio (INR). Bleeding complications are common and we speculate if this is related to the limitation of INR only reflecting the initiation steps of the haemostatic process. The objective of the present review was to reassess the evidence for using INR as a tool to guide administration of prothrombin complex concentrates (PCC) to OAC patients. A Medline and Cochrane database search was conducted using the following keywords: prothrombin complex concentrate, reversal of oral anticoagulation and international normalized ratio (INR). Thirty-three articles were contracted and a total of ten studies were eligible after applying inclusion and exclusion criteria encompassing only 339 patients. No consensus regarding optimal target INR value to aim for when reversing OAC was found. In three of the studies it was reported that patients reaching their target INR continued to bleed, whereas three studies reviewed reported good haemostatic response also in patients that did not reach their target INR. The present review found limited evidence for the usefulness of INR as a tool to monitor and guide reversal of OAC induced coagulopathy in patients with PCC, which is expected given that it is a plasma-based assay only reflecting a limited part of the haemostatic process.