Abstract Background Atrial fibrillation (AF) is often asymptomatic, and screening is not routinely undertaken. Objective Evaluate the feasibility and effectiveness of a population-based case finding program and to identify the enablers of and/or barriers to its implementation. Methods We conducted a cross-sectional study of a health care case finding program for AF from 1 January 2016, to 31 December 2017, that included 48 336 people ≥60 years of age in the region of Terresde l’Ebre (Catalonia, Spain). We analysed the effect on the prevalence of AF and, stratified by age, on the incidence of new diagnoses of AF. We assessed the sociodemographic and clinical variables related to the realization of a case finding. Results A total of 32 090 (62.4%) people were screened for AF. We observed a significant increase in the AF prevalence after 2 years of program intervention (5.9–7.7%; P < 0.001). The detection of new AF cases was significantly higher in the case finding group across the whole of the age range, and 765 (2.6%) new AF cases were diagnosed using case finding. The factors that were significantly associated with an underuse of case finding were: age <70 years, urban residence, institutionalized status, Pfeiffer score ≥2, Charlson score >3 and number of visits <7/year. Conclusions A health care program of case finding is feasible and is associated with a significant increase in the prevalence and incidence of AF. The results depend on factors such as the ease of access to health care, age, place of residence and comorbidities.