Anticoagulation for Chronic Non Valvular Atrial Fibrillation in the Elderly: A Review

Abstract

Atrial Fibrillation (AF) is a major risk factor for disabling ischaemic stroke due to embolism from the left atrium. AF is the most frequent arrhymia in the elderly and its prevalence increases with age [1]. The true prevalence is difficult to determine as a substantial proportion of patients will be asymptomatic or have subclinical disease. However, two thirds of patients with AF will be at least 75 years old [2], and of the patients over 75 years 10% will have AF. The influence of AF on health outcomes increases with age in that 71% of strokes that occur in patients with AF are over 70 years [3] and that patient outcomes are worse in patients with AF than in those without AF [4].Current guidelines recommend the use of anticoagulants to reduce the risk of embolic stroke in patients with AF [5,6]. As with any pharmacological intervention there are risk and benefits with anticoagulant therapy. The benefit is the decrease in stroke at the *Corresponding author: Nigel P Murray, Department of Medicine, University Finis Terrae, Providencia, Santiago, Chile, Tel: +56 274980507; E-mail: nigelpetermurray@gmail.com There are simple clinical tools to assess the benefits and risks of anticoagulant therapy using easily available clinical data in the older patient.To assess benefit due to stroke risk, the CHADS2 score (congestive heart failure, hypertension, age >75 years, diabetes mellitus and previous stroke or transient ischemic attack) is commonly used [7]. This tool which was developed in a population of elderly patients, gives one point for the presence of each risk factor and two points for a previous stroke or TIA. The risk of embolic stroke increases with each point of the CHADS 2 tool, from 1.9% annual stroke risk with 0 points to 18.2% anual stroke risk in patients with a score of 6 points [8]. Most guidelines recomend the use of anticoagulation in patients with a CHADS 2 score of 1 or greater. In a study of 773 patients older than 75 years with AF, 49% had congestive heart failure, 83% hypertension, 21% diabetes and 32% previous stroke or TIA [9]. Or in other words nearly all patients over 75 years meet the recomendations for anticoagulation.To assess the risk for hemorrhage there are three prediction tools; firstly the HAS-BLED score [10], which includes hypertension; abnormal renal/liver function, stroke, bleeding history or predisposition, Labile International Normalized Ratio, elderly (>65 years), drugs/alcohol concomitantly and has been incorporated into the European and Canadian guidelines on the management of patients with AF [6,11]. The HAS-BLED score is designed to estimate the 1 year risk of major bleeding (intracranial, hospitalization, hemoglobin decrease of >2gr/dl or need for transfusion) in patients older than 65 years. It is simple to use, and the trade-off in terms of the benefits and risks of oral anticoagulation demonstrates that in the majority of patients with AF, the risk of bleeding outweighs the potential benefit of anticoagulation if the HAS-BLED score excedes the CHADS2 2 score. The HEMO...