[2014] Rationale and impact These sections briefly explain why the committee made the recommendations and how they might affect practice. Detection and diagnosis Why the committee made the recommendations The evidence did not support changing the recommended diagnostic tests to either replace 12-lead ECG as the test to confirm persistent atrial fibrillation or replace pulse palpation as the initial step for persistent atrial fibrillation in a 2-step strategy. The committee clarified that 12-lead ECG should be used as the test to confirm atrial fibrillation, to prevent the use of less accurate ECG devices, such as mobile and lead-I ECG devices. The committee agreed that, although the evidence showed that accuracy varied, there was some evidence that new devices were accurate and showed promise. It was noted that NICE has produced diagnostics guidance on lead-I ECG devices for detecting symptomatic atrial fibrillation using single time point testing in primary care. The committee made a research recommendation on tests to diagnose persistent atrial fibrillation to encourage further high-quality research in this area to guide future practice. The committee agreed that the evidence on tests to detect paroxysmal atrial fibrillation was not clear enough to warrant a change in practice from the 2014 recommendation. However, the evidence did show that longer durations of detection increased accuracy. The committee made a research recommendation on tests to diagnose paroxysmal atrial fibrillation. How the recommendations might affect practice The recommendations reflect current good practice and are unlikely to have an impact on practice. Return to recommendations Stroke risk Why the committee made the recommendations The committee decided to prioritise identifying people above or below a certain risk threshold (discrimination) in its interpretation of the evidence rather than estimating a person's risk of stroke in absolute terms. 