Risk assessment in atrial fibrillation: not all factors are created equal

Abstract

This editorial refers to ‘Comparison of CHADS2 and CHA2DS2-VASC anticoagulation recommendations: evaluation in a cohort of atrial fibrillation ablation patients’ by R.A.Winkle et al ., on page 195. Oral anticoagulation (OAC) reduces the risk of stroke and improves survival in patients with atrial fibrillation (AF). Despite these benefits, the risks of long-term OAC are not trivial and include intracranial haemorrhage. Therefore, the decision to use OAC to prevent stroke in patients with AF is heavily dependent upon the underlying risk and potential benefit for each individual patient. Following its derivation in the National Registry of Atrial Fibrillation, the CHADS2 score has become the most familiar and widely used risk stratification tool for patients with AF.1 The score assigns 1 point each for congestive heart failure, hypertension, age ≥75, and diabetes, and 2 points for a history of prior stroke or transient ischaemic attack (TIA). Rates of stroke range from 1.2 events per 100 patient-years for patients with a score of 0, to >6 events per 100 patient-years in patients with scores of ≥3. However, the upper confidence limit of the stroke rate for patients with a CHADS2 score of 1 is nearly four events per 100 patient-years—significantly higher than a comparable non-AF population. Thus, while CHADS2 can identify patients at high risk of stroke, it is less accurate in resolving risk at the lower end of the spectrum. The CHA2DS2-VASc algorithm was developed to discriminate in a better manner patients at low risk.2 The score subdivides age (65–74 receives 1 point, ≥75 receives 2), and adds female sex (1 point) and the presence of atherosclerotic vascular disease (1 point). As a result, the CHA2DS2-VASc score can provide better risk discrimination in patients with CHADS2 scores of 0–1. …