Clinical Outcomes According to Age and Atrial Fibrillation Type: Insights from the Multicentre REGUEIFA Registry.

Background/Objectives: Atrial fibrillation (AF) represents the most common sustained cardiac arrhythmia, and its incidence rises markedly with advancing age. The relative prognostic impact of age compared with AF type remains uncertain. This study assessed the association between age, AF type, and clinical outcomes in a large real-world AF cohort. Methods: This study was based on data from the prospective, observational, multicentre REGUEIFA registry, which includes consecutive patients with AF treated at eight hospitals in northwestern Spain. Patients were stratified by age and AF type. Baseline characteristics, comorbidities, treatments, and risk scores were collected. Patients were followed for at least 2 years, and outcomes included all-cause mortality, heart failure (HF) worsening, stroke, and a composite endpoint. Results: A total of 997 patients were included. Increasing age was associated with a worse clinical profile, with higher comorbidity burden and increased thromboembolic and bleeding risk. During follow-up, adverse events increased stepwise with age, including mortality, HF worsening, and the composite endpoint. AF type was not independently associated with outcomes after multivariable adjustment. Rhythm-control strategy was independently associated with a lower risk of the composite endpoint. Age remained an independent predictor of all outcomes. Risk of the composite endpoint increased across age groups (HR 2.01 for 75-84 years; 2.34 for 85-89 years; 6.50 for ≥90 years vs. <75 years). Each additional year of age was associated with a 9% higher mortality risk (HR 1.09; 95% CI 1.06-1.13). Conclusions: In this prospective real-world cohort of patients with AF, age was the strongest and most consistent predictor of adverse clinical outcomes, whereas AF type lost prognostic significance after adjustment. These findings support age and overall clinical burden as key determinants of prognosis, favouring a patient-centred approach over AF subtype classification.