Reliable Identification of ‘Truly Low’ Thromboembolic Risk in Patients Initially Diagnosed With ‘Lone’ Atrial Fibrillation: The Belgrade Atrial Fibrillation Study

Study Questions:

What is the predictive ability of the CHA2DS2-VASc, CHADS2, and van Walraven risk stratification schemes in a cohort of ‘lone’ AF patients with a 12-year follow-up?


The investigators conducted a registry-based, observational cohort study of 345 patients initially diagnosed with ‘lone’ AF between 1992 and 2007. A multivariable logistic regression analysis was used to study the relationship between clinical characteristics, clinical type of AF, and van Walraven, CHADS2, and CHA2DS2-VASc scores of 0 with the use of oral anticoagulation during follow-up.


At baseline, all patients had the CHADS2 and van Walraven scores of 0, and 262 (75.9%) had a CHA2DS2-VASc score = 0. During follow-up (or within a year prior to stroke), 228 (66.1%), 234 (67.8%), and 150 patients (43.5%) retained the CHADS2, van Walraven, and CHA2DS2-VASc scores of 0, respectively. The overall rate of ischemic stroke was 0.19 (95% confidence interval [CI], 0.18-0.20) per 100 patient-years. In the multivariable analysis, only the CHA2DS2-VASc score of 0 was significantly related to the absence of stroke (odds ratio, 5.1; 95% CI, 1.5-16.8; p = 0.008). Only the CHA2DS2-VASc score had a significant prediction ability (c-statistic 0.72 [0.61-0.84], p = 0.031).


The authors concluded that CHA2DS2-VASc score reliably identified the ‘lone’ AF patients who were at ‘truly low risk’ for thromboembolism, and was the only tested risk stratification scheme with a significant predictive ability for thromboembolism amongst lone AF patients.


In the present study, a CHA2DS2-VASc score of 0 had the best predictive value for the absence of ischemic stroke in ‘lone’ AF patients, as compared to CHADS2 and van Walraven scores of 0. This is the largest validation of these scores in a prospective cohort of patients with first-diagnosed ‘lone’ AF, with the diagnostic criteria for ‘lone’ AF being strictly applied. Due to the dynamic nature of stroke risk factors, thromboembolic risk of an individual AF patient must be regularly re-assessed during the follow-up, even if the baseline stroke risk was ‘truly low.’ Greater efforts should be made to identify AF patients with the ‘truly low risk’ who would need no antithrombotic therapy at all, whilst all other AF patients with one or more stroke risk factors should be considered for oral anticoagulation.

Clinical Topics: Arrhythmias and Clinical EP, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Thromboembolism, Odds Ratio, Registries, Stroke, Follow-Up Studies, Atrial Fibrillation, Risk Factors, Confidence Intervals, Risk Assessment, Logistic Models

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