Although some studies suggest that PAF is associated with a lower risk of stroke than persistent or permanent AF, patients with PAF generally are younger and have a lower prevalence of other stroke risk factors, and clinical trial data suggest that PAF confers a relative risk of stroke similar to persistent or permanent AF when controlling for associated stroke risk factors.14-17 Pending further evidence, it seems reasonable to treat patients with PAF in a manner similar to those with persistent and permanent AF; thus, our risk-based treatment recommendations apply to patients with PAF and per- sistent and permanent AF. 1.4.2 Independent Risk Factors for Stroke in Patients With AF: Two recent systematic reviews have identi ed clinical and echo- cardiographic factors that are independently associated with an increased risk of stroke in patients with AF.18,19 The individual studies from these systematic reviews, in addition to articles identi ed in an updated literature search performed for this guideline, are summarized in Tables S1 through S12 (tables that contain an S before the number denote supplementary tables not contained in the body of the article and available instead in an online data supplement; see the Acknowledgments for more information). In terms of clinical applicability, the most consistently identi ed risk factors for ischemic stroke among patients with AF are a history of ischemic stroke or transient ischemic attack (TIA) the strongest dichotomous predictor of stroke risk older age, hypertension, and diabetes. Although impaired left ventricular systolic function is a risk factor for stroke in AF, there are con icting data about whether a history of congestive heart failure per se raises the risk of ischemic stroke in AF. 