Advances in Stroke Prevention in Atrial Fibrillation: Enhanced Risk Stratification Combined With the Newer Oral Anticoagulants

Abstract

Patients with atrial fibrillation (AF) have an increased stroke risk compared with those in sinus rhythm, although the absolute risk for individual patients is modulated by the presence of various additional risk factors. Patient selection for oral anticoagulation for stroke prevention is based on risks of stroke and bleeding. Although CHADS 2 (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke or transient ischemic attack) is the most widely used scheme for evaluating stroke risk in patients with AF, several other stroke risk factors are not included; therefore, many patients' stroke risk may be underestimated, contributing to the underuse of anticoagulants. Furthermore, a substantial proportion of patients are categorized as being at moderate risk (CHADS 2 = 1), and there has been some ambiguity regarding optimum thromboprophylaxis in this group. -VASc = 0), who are unlikely to benefit from antithrombotic therapy. For all others, an oral anticoagulant may be the preferred approach, simplifying clinical decision making. Implementation of CHA 2 DS 2 -VASc may also result in an increased proportion of patients receiving anticoagulation. The emergence of newer oral anticoagulants that can be given without routine coagulation monitoring, with improved benefit-risk profiles vs vitamin K antagonists, promises to simplify therapy for patients with AF at risk of stroke. This, coupled with advances in stroke risk stratification, is expected to improve patient outcomes and reduce the burden of AF-related stroke. IntroductionAtrial fibrillation (AF) is the most frequent clinically relevant cardiac arrhythmia encountered in the outpatient clinic, 1 affecting ∼ 1% of the US population and up to 10% of individuals age ≥80 years, with a higher prevalence among men than among women at all ages. 2 It is predicted that the prevalence of AF will continue to rise in the coming decades. 3 Patients with AF are at an increased risk of cardioembolic stroke; their risk is approximately 5-fold greater than for patients in sinus rhythm, 4 although the absolute risk for individual patients is highly variable depending on the presence or absence of various risk factors. 5,6

Stroke and Bleeding Risk in Atrial Fibrillation: Navigating the Alphabet Soup of Risk‐Score Acronyms (CHADS2, CHA2DS2‐VASc, R2CHADS2, HAS‐BLED, ATRIA, and More)

“…In summary, the performance of the CHA 2 DS 2 ‐VASc score for predicting those at high risk of stroke/TE was comparable with other contemporary risk‐stratification schemes such as the Eighth American College of Chest Physicians Guidelines, National Institute for Health and Clinical Excellence (NICE), and modified CHADS 2 . The CHA 2 DS 2 ‐VASc score is currently recommended by the European guidelines on AF management as the main scheme to assess patient stroke risk because of its ability to identify low‐risk patients, as this was the principal group that does not need anticoagulation …”

“…With the introduction of the CHA 2 DS 2 ‐VASc score, categorization of AF patients improved significantly with respect to selecting patients at low risk of stroke (essentially, a CHA 2 DS 2 ‐VASc of 0 in males or CHA 2 DS 2 ‐VASc of 1 in females) . These are the patients with lone AF without structural heart disease and age <65 years.…”

“…In 27 458 patients taking warfarin from the UK General Practice Database, adhering to 70% threshold resulted in 79% reduction in risk of stroke when compared with patients with a TTR <30% . With the increased use of novel OACs, the problem of poor anticoagulation control is likely to be partly solved, as they do not depend upon INR control; but high‐quality anticoagulation control for warfarin patients remains of paramount importance and is an important issue in the decision‐making process regarding who is likely to fare well with being started on warfarin rather than a novel OAC …”

“…This score assigns 2 points to prior stroke, TIA, or TE, and 6,32 With the introduction of the CHA 2 DS 2 -VASc score, categorization of AF patients improved significantly with respect to selecting patients at low risk of stroke (essentially, a CHA 2 DS 2 -VASc of 0 in males or CHA 2 DS 2 -VASc of 1 in females). 4,5,33 These are the patients with lone AF without structural heart disease and age <65 years. Such ''truly lowrisk'' patients do not need any antithrombotic therapy, and the subsequent step would be that all other AF patients, those with ≥1 stroke risk factor, require appropriate antithrombotic prophylaxis, which is essentially OAC.…”