Phase-Aligned Atrial Fibrillation Mapping

Cardiac arrhythmia in the upper chamber of the heart (atrial fibrillation) can be cured by burning. Physicians burn very small pieces of abnormal tissue. It is important to know where to burn. The investigators propose a new way to find out where to burn. The investigators will use a new way to analyze electrical signals inside the heart and build a new electric map. The study may lead to the development of new technology. In the future, novel technology may increase the success rate and the number of cured atrial fibrillation patients. This study is a retrospective study of data collected during routine clinical care: atrial fibrillation ablations. The investigators will compare intracardiac electrograms and atrial activation maps in patients who had successful ablation outcomes (no recurrence within 1 year) and those who experienced a recurrence of arrhythmia within 1 year after the procedure.

Inclusion Criteria: 1. Records of patients with persistent AF who underwent pulmonary vein isolation (PVI) with any additional AF ablation strategy with available stored digital AF mapping data. Persistent AF is defined as AF lasting more than 7 days. 2. One/First AF ablation procedure (no prior atrial ablation procedures) 3. Documented complete pulmonary vein isolation at the end of the ablation 4. Available uniform, high-quality (as described below) clinical data required to detect AF recurrence during ≥ 1 year after ablation, and/or ECG monitoring (implantable loop recording or repeated long-term ECG monitoring via ECG patch or similar) Exclusion Criteria: 1. Familial AF, AF as a syndrome in rare diseases (cardiomyopathies / WPW/ channelopathies). 2. Missing data of exposure (AF ablation map), outcome (definition of cases and controls), or covariates