Risk factors and outcomes of new-onset atrial fibrillation in patients hospitalized in an internal medicine ward: a case–control study

Atrial fibrillation (AF) is a frequent pathology in Internal Medicine departments. The aim of our study was to identify the risk factors associated with the development of new-onset AF during hospitalization and to evaluate its outcome as in-hospital mortality. We conducted a retrospective case–control study on a cohort of 14,179 patients admitted to an internal medicine department. We included in the study the patients who did not have an anamnestic history of AF, who presented a sinus rhythm at the time of admission and who developed a new-onset AF during hospitalization. For each of these cases, two controls were enrolled who were not affected by AF. The patients included in the study were 588, including 196 cases and 392 controls. Patients who developed AF during hospitalization had significantly more comorbidity than controls. The most frequent causes for hospitalization were sepsis, significantly higher in the case group. From the results of the multivariate analysis, the factors related independently to the development of AF were the presence of a number of comorbidities ≥ 3 (OR = 1.52; p = 0.017), sepsis as a reason of hospitalization (OR = 2, 16; p = 0.001) and glycemic value at the admission ≥ 130 mg/dL (OR = 1.44; p = 0.047). Both the length of hospital stay and in-hospital mortality were higher in the group of patients who developed AF, with a statistically significant difference compared to controls (p < 0.001).