The Realistic Computational Electrophysiology Simulations for the Targeted Treatment of Atrial Fibrillation (ReCETT-AF) study is a research project investigating why therapies for atrial fibrillation vary in success for patients. AF is a common heart rhythm disorder in which irregular electrical activity in the atria leads to an abnormal heartbeat. ReCETT-AF aims to better understand the electrical circuits that sustain AF by combining advanced cardiac imaging, detailed electrical recordings obtained during routine ablation procedures, and computer modelling of each patient’s heart. Participants undergo a pre-procedure cardiac MRI scan, additional electrical measurements during their ablation procedure, and structured follow-up after treatment. Using these data, researchers are developing realistic computational simulations of atrial electrophysiology to identify the mechanisms driving AF in individual patients. The long-term goal of the study is to enable more personalised and targeted treatment strategies, including ablation, improving treatment outcomes for people living with atrial fibrillation.