Incident Atrial Fibrillation and Flutter in Patients With Pulmonary Arterial Hypertension: Influence of Right Ventricular Dilatation and Reduced Right Atrial Function

Journal of the American Heart Association, Volume 15, Issue 9 , May 5, 2026. BackgroundThe relationship between right atrial (RA) structural and functional remodeling and risk of incident atrial fibrillation/flutter (AF/AFL) in pulmonary arterial hypertension remains poorly defined.MethodsIn a multicenter observational cohort study of 326 patients with pulmonary arterial hypertension, we evaluated associations between RA structure and function, as determined by echocardiography, and incident AF/AFL.

Incidence rates were calculated using time‐to‐event analysis. Cox proportional hazards models identified factors associated with incident AF/AFL, and Harrell's C‐statistics compared predictive performance.

Survival decision tree and restricted cubic spline analyses identified thresholds associated with increased risk of AF/AFL.ResultsThe mean age was 51±15 years, 79% were women, and the mean REVEAL (Registry to Evaluate Early and Long‐Term Outcomes in Pulmonary Arterial Hypertension) Lite score was 7.4±2.9. Over a median follow‐up of 6.1 years, 56 patients (17.1%) developed AF/AFL, corresponding to an incidence rate of 25.3 cases (95% CI, 19.5–32.8) per 1000 person‐years.

Each 5% decrease in RA emptying fraction (hazard ratio [HR], 1.38 [95% CI, 1.03–1.86];P=0.03) and each 1‐cm increase in right ventricular basal diameter (HR, 1.55 [95% CI, 1.18–2.05];P=0.002) were independently associated with 38% and 55% higher hazards of incident AF/AFL, respectively. The C‐statistics for predicting incident AF/AFL were 0.62 for RA emptying fraction and 0.65 for right ventricular basal diameter.

Survival decision tree and restricted cubic spline analyses identified thresholds for right ventricular basal diameter (≥5.4 cm) and RA emptying fraction (<17% and <45%) associated with increased AF/AFL risk.ConclusionsLarger right ventricular basal diameter and lower RA emptying fraction are associated with increased risk of incident AF/AFL in patients with pulmonary arterial hypertension and may help identify individuals at higher risk.