Atrial Fibrillation Detected before or after Stroke: Role of Anticoagulation

Abstract

BackgroundAtrial fibrillation (AF) known before ischemic stroke (KAF) has been postulated to be an independent category with a recurrence risk higher than that of AF detected after stroke (AFDAS). However, it is unknown whether this risk difference is confounded by pre‐existing anticoagulation, which is most common in KAF and also indicates a high ischemic stroke recurrence risk.MethodsIndividual patient data analysis from 5 prospective cohorts of anticoagulated patients following AF‐associated ischemic stroke. We compared the primary (ischemic stroke recurrence) and secondary outcome (all‐cause death) among patients with AFDAS versus KAF and among anticoagulation‐naïve versus previously anticoagulated patients using multivariable Cox, Fine‐Gray models, and goodness‐of‐fit statistics to investigate the relative independent prognostic importance of AF‐category and pre‐existing anticoagulation.ResultsOf 4,357 patients, 1,889 (43%) had AFDAS and 2,468 (57%) had KAF, while 3,105 (71%) were anticoagulation‐naïve before stroke and 1,252 (29%) were previously anticoagulated. During 6,071 patient‐years of follow‐up, we observed 244 recurrent strokes and 661 deaths. Only pre‐existing anticoagulation (but not KAF) was independently associated with a higher hazard for stroke recurrence in both Cox and Fine‐Gray models. Models incorporating pre‐existing anticoagulation showed better fit than those with AF category; adding AF‐category did not result in better model fit. Neither pre‐existing anticoagulation nor KAF were independently associated with death.ConclusionOur findings challenge the notion that KAF and AFDAS are clinically relevant and distinct prognostic entities. Instead of attributing an independently high stroke recurrence risk to KAF, future research should focus on the causes of stroke despite anticoagulation to develop improved preventive treatments. ANN NEUROL 2023;94:43–54

Association of the Timing of Atrial Fibrillation Detection and Insular Involvement With the Risk of Embolic Events After Acute Ischemic Stroke

“…A recent combined cohort study including the cohort of SAMURAI-NVAF showed that no significant difference was observed between patients with AFDAS, which was defined in the same way as in the present study, and KAF regarding the risk of recurrent ischemic stroke. 20 However, patients with AFDAS had a lower risk of embolic events than those with KAF in the present study. This discrepancy might be explained by the fact that the prevalence of sustained AF in patients with AFDAS in the present study was lower than that in the combined cohort study (36.3% vs 64.6%).…”

Diagnosis and Management of Atrial Fibrillation in Acute Ischemic Stroke in the Setting of Reperfusion Therapy: Insights and Strategies for Optimized Care

“…It raises the possibility that the difference in risk may be influenced by pre-existing anticoagulation, which is more common in KAF and signifies a heightened risk of ischemic stroke recurrence [72]. A recent study by Lyrer et al [73] challenged the idea that KAF and AFDAS are distinct prognostic entities and suggest that, rather than solely attributing a high stroke recurrence risk to KAF, future research should concentrate on understanding the causes of stroke in patients despite anticoagulation treatment to develop more effective preventive measures.…”

Emerging Management Challenges Posed by Atrial Fibrillation Detected After Stroke

“…Although this study 6 is important, it has several limitations worth noting. Authors lack data on AF burden, which is known to be associated with ischemic stroke risk in AF.…”

“…In a study published in this issue of Annals of Neurology , Lyrer et al 6 analyzed data from a multicenter study of patients with acute ischemic stroke in the setting of AF. They evaluated the risk of recurrent stroke in patients with AF, comparing those with two different categories of AF detection: AFDAS versus those with Known AF.…”

“…As we continue to improve and refine secondary stroke prevention, new challenges and new questions emerge. As shown by Lyrer et al, 6 there is no substitute for randomized trial data to help avoid the confounding inherent in observational data that has led many to treat AFDAS and Known AF as distinct clinical entities. Well‐designed and adequately powered studies are urgently needed to determine optimal stroke prevention therapy for patients with AFDAS.…”