In patients with device-detected atrial fibrillation the risk of stroke appears low (1% per year) compared to patients with ECG-detected atrial fibrillation, even in patients with long episodes. Anticoagulation can slightly reduce stroke risk, but also increase major bleeding. This is the main finding of a sub-analysis of the NOAH – AFNET 6 trial presented by Dr Nina Becher, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany, in the late-breaking clinical trials session at the annual congress of the American Heart Association (AHA) in Philadelphia, USA, and published today in the European Heart Journal (1).