Atrial fibrillation in young hospitalized patients: Clinical characteristics, predictors of new onset, and outcomes.

Background: Atrial fibrillation (AF) in young adults is an uncommon and not well studied entity.

Methods: Consecutive patients aged 18-45 years admitted to internal or cardiology services in a large tertiary medical center (January 1, 2009 through December 31, 2019) were included. Clinical, electrocardiographic, and echocardiographic data were compared between patients with and without AF at baseline. Predictors of new-onset AF in the young were identified using multivariate Cox regression model among patients free of baseline AF.

Results: Final cohort included 16,432 patients with median age of 34 (IQR 26-41) years of whom 8914 (56 %) were men. Patients with AF at baseline (N = 366; 2 %) were older, more likely to be men, and had higher proportion of comorbidities and electrocardiographic conduction disorders. Male sex, increased age, obesity, heart failure, congenital heart disease (CHD) and the presence of left or right bundle branch block were all independently associated with baseline AF in a multivariate model (p < 0.001 for all). Sub-analysis of 10,691 (98 %) patients free of baseline AF identified 85 cases of new-onset AF during a median follow up of 3.5 (IQR 1.5-6.5) years. Multivariate model identified increased age, heart failure, and CHD as independent predictors of new-onset AF. Finally, the CHARGE-AF risk score outperformed the CHADS-VASc score in AF prediction [AUC of ROC 0.75 (0.7-0.8) vs. 0.56 (0.48-0.65)].

Conclusions: AF among hospitalized young adults is not rare. Screening for new-onset AF in young post hospitalization patients may be guided by specific clinical predictors and the CHARGE-AF risk score.