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Background Short and rare episodes of atrial fibrillation (AF) are commonly detected using implanted devices (device‐detected AF) in patients with prior stroke or transient ischemic attack (TIA). The effectiveness and safety of oral anticoagulation in patients with prior stroke or TIA and device‐detected AF but with no ECG‐documented AF is unclear. Methods and Results This prespecified analysis of the NOAH‐AFNET 6 (Non‐Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes) trial with post hoc elements assessed the effect of oral anticoagulation in patients with device‐detected AF with and without a prior stroke or TIA in the randomized, double‐blind, double‐dummy NOAH‐AFNET 6 trial. Outcomes were stroke, systemic embolism, and cardiovascular death (primary outcome) and major bleeding and death (safety outcome). A prior stroke or TIA was found in 253 patients with device‐detected AF randomized in the NOAH‐AFNET 6 (mean age, 78 years; 36.4% women). There was no treatment interaction with prior stroke or TIA for any of the primary and secondary time‐to‐event outcomes. In patients with a prior stroke or TIA, 14 out of 122 patients experienced a primary outcome event with anticoagulation (5.7% per patient‐year). Without anticoagulation, there were 16 out of 131 patients with an event (6.3% per patient‐year). The rate of stroke was lower than expected (anticoagulation: 4 out of 122 [1.6% per patient‐year]; no anticoagulation: 6 out of 131 [2.3% per patient‐year]). Numerically, there were more major bleeding events with anticoagulation in patients with prior stroke or TIA (8 out of 122 patients) than without anticoagulation (2 out of 131 patients). Conclusions Anticoagulation appears to have ambiguous effects in patients with device‐detected AF and a prior stroke or TIA in this hypothesis‐generating analysis of the NOAH‐AFNET 6 in the absence of ECG‐documented AF, partially due to a low rate of stroke without anticoagulation.

BackgroundThe standard 12-lead ECG has been shown to be of value in characterizing atrial conduction properties. The added value of extended ECG recordings (longer recordings from more sites) has not been systematically explored yet.ObjectiveThe aim of this study is to employ an extended ECG to identify characteristics of atrial electrical activity related to paroxysmal vs. persistent atrial fibrillation (AF).MethodsIn 247 participants scheduled for AF ablation, an extended ECG was recorded (12 standard plus 3 additional leads, 5 min recording, no filtering). For patients presenting in sinus rhythm (SR), the signal-averaged P-wave and the spatiotemporal P-wave variability was analyzed. For patients presenting in AF, f-wave properties in the QRST (the amplitude complex of the ventricular electrical activity: Q-, R-, S-, and T-wave)-canceled ECG were determined.ResultsSignificant differences between paroxysmal (N = 152) and persistent patients with AF (N = 95) were found in several P-wave and f-wave parameters, including parameters that can only be calculated from an extended ECG. Furthermore, a moderate, but significant correlation was found between echocardiographic parameters and P-wave and f-wave parameters. There was a moderate correlation of left atrial (LA) diameter with P-wave energy duration (r = 0.317, p < 0.001) and f-wave amplitude in lead A3 (r = −0.389, p = 0.002). The AF-type classification performance significantly improved when parameters calculated from the extended ECG were taken into account [area under the curve (AUC) = 0.58, interquartile range (IQR) 0.50–0.64 for standard ECG parameters only vs. AUC = 0.76, IQR 0.70–0.80 for extended ECG parameters, p < 0.001].ConclusionThe P- and f-wave analysis of extended ECG configurations identified specific ECG features allowing improved classification of paroxysmal vs. persistent AF. The extended ECG significantly improved AF-type classification in our analyzed data as compared to a standard 10-s 12-lead ECG. Whether this can result in a better clinical AF type classification warrants further prospective study.