Background <p>Evidence suggests a benefit of a rhythm control approach in patients with a recent diagnosis of atrial fibrillation (AF). This study sought to evaluate clinical characteristics, treatment strategies and outcomes in patients with first diagnosed AF (FDAF) undergoing a non-invasive rhythm control strategy in an emergency department (ED).</p> Methods <p>This analysis uses data from the Heidelberg Registry of Atrial Fibrillation (HERA-FIB). HERA-FIB is a retrospective single-centre observational study which consecutively included patients presenting to the ED of the University Hospital of Heidelberg between June 2009 and March 2020 with a sequential follow-up for all-cause mortality, stroke, major bleeding events and myocardial infarction (MI). Outcomes of patients with FDAF were related to treatment strategy (non-invasive rhythm vs. rate control).</p> Results <p>Among the 2,758 (27%) patients who presented with FDAF, a non-implementation of a non-invasive rhythm control strategy at admission was observed in 75.4% and associated with an excess of all-cause mortality hazard ratio (HR): 1.61 (95%CI 1.30–1.99), <i>p</i> &lt; 0.0001 and incident MI HR: 1.88 (95% CI 1.22–2.90), <i>p</i> = 0.0043 during follow-up. The non-implementation of a non-invasive rhythm control remained an independent predictor for all-cause mortality and MI even after adjustment for significant univariate variables with an adjusted HR of 1.52 (95%CI: 1.14–2.04, <i>p</i> = 0.0043) and 1.89 (95%CI: 1.03–3.45, <i>p</i> = 0.0392), respectively.</p> Conclusion <p>Real-world data from FDAF patients presenting to an ED showed a benefit regarding all-cause mortality and MI favouring a non-invasive rhythm control strategy. Further prospective research is needed to validate this hypothesis.</p> Trial registration <p>The trial was registered at ClinicalTrials.gov Identifier: NCT05995561.</p>