Stroke prevention in atrial fibrillation: An Asian perspective

Stroke and bleeding risk in atrial fibrillation

Non-valvular atrial fibrillation (AF) is the most common cardiac arrhythmia in the clinical setting. AF increases both the risk and severity of strokes, and is associated with substantial morbidity and mortality. Despite the clear net clinical benefit of oral anticoagulants (OACs) in patients with AF at risk for stroke, major bleeding events, especially intracranial bleeds, may be devastating. In the last decade, four new OACs have been approved for stroke prevention in patients with AF and are at least as effective as warfarin with better bleeding profiles. These new agents have changed and simplified our approach to stroke prevention because the threshold for initiation of OACs is lowered. An important clinical practice shift is the initial identification of "low-risk" patients who do not need antithrombotic therapy, with low-risk comprising CHA2DS2-VASc {Congestive heart failure, Hypertension, Age ≥75 years (double), Diabetes mellitus, previous Stroke/transient ischemic attack/thromboembolism (double), Vascular disease, Age 65-74 years, and female gender (score of 0 for males and 1 for female)}. Subsequent to this step, effective stroke prevention consisting of OACs can be offered to patients with one or more stroke risk factors. Apart from stroke risk, another consideration is bleeding risk assessment, with a focus on the use of the validated HAS-BLED {Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile international normalized ratio (INR), Elderly (age >65 years), drugs or alcohol concomitantly} score. A high HAS-BLED score can flag patients potentially at risk for bleeding, and alert clinicians to the need for careful review and follow up, and the need to consider potentially correctable bleeding risk factors that include uncontrolled hypertension, labile INRs, concomitant aspirin use, and alcohol excess.

New oral anticoagulants may be particularly useful for asian stroke patients

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

Stroke And Bleeding Risk Assessment: Where Are We Now?

Atrial fibrillation (AF) is one of major problems of the contemporary cardiology. Ischaemic stroke is a common complication of the AF, and effective prophylaxis requires treatment with oral anticoagulants. The purpose of this current review article is to provide an overview of the various stroke and bleeding risk assessment scores that help decision making with respect to thromboprophylaxis. Particular focus is made on the currently guideline-recommended stroke and bleeding risk scores, such as CHA₂DS₂-VASc (congestive heart failure or left ventricular dysfunction, hypertension, age ≥75, diabetes, stroke, vascular disease, age 65-74 and sex category [female]) and HAS-BLED (uncontrolled hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly [e.g. age >65, frail condition], drugs [e.g. aspirin, nonsteroidal anti-inflammatory drugs]/excessive alcohol) is made. Future directions for improvement of predictive ability of risk assessment with clinical factors and biomarkers are also discussed.