Danny Mohama, Pitchaya Worapongsatitaya, Bettia Celestin, Felipe Kazmirczak, Shadi P. Bagherzadeh, Veronica Daniel, Kurt W. Prins, Sasha Z. Prisco, E. Kenneth Weir, Stephen L. Archer, Roham Zamanian, Francois Haddad, Thenappan Thenappan
Abstract Background The relationship between right atrial (RA) structural and functional remodeling and risk of atrial fibrillation/flutter (AF/AFL) in pulmonary arterial hypertension (PAH) is understudied. This is important due to the prognostic implications of AF/AFL in PAH. Methods In a multicenter cohort study comprised of 326 PAH patients with no prior history of AF/AFL, we evaluated how RA structure and function, as determined by echocardiography, were associated with AF/AFL. We calculated the incident rate (IR) of AF/AFL using time to event analysis. Cox proportional hazards analyses defined factors associated with incident AF/AFL and Harrell’s C-statistics compared the ability of different variables to predict incident AF/AFL. Survival decision tree and restricted cubic spline analyses identified thresholds associated with incident AF/AFL. Results In the combined PAH cohort, the mean age was 51±15 years, 79% were female, and the mean REVEAL lite score was 7.4±2.9. Over a median follow-up of 6.1 years, 56 patients (17.1%) developed AF/AFL with an IR of 25.3 cases (95% CI: 19.5 - 32.8) per 1000 person-year. On multivariable Cox proportional hazards analysis, every 5% decrease in RA emptying fraction (RAEF, HR: 1.38, 95% CI: 1.03 – 1.86, p =0.030) and one centimeter increase in right ventricular (RV) basal diameter (HR: 1.55 95% CI: 1.18 – 2.05, p =0.002) were independently associated with 38% and 56% increased hazards of incident AF/AFL, respectively. The C-statistics of RAEF and RV basal diameter to predict incident AF/AFL were 0.62 and 0.65, respectively. Survival decision tree and restricted cubic spline analyses identified informative thresholds for RAEF at <17 and 45% and for RV basal diameter at ≥5.4 cm for increased hazards of incident AF/AFL. Conclusion Lower RAEF and higher RV basal diameter are associated with increased risk of incident AF/AFL in PAH patients. These data could help identify PAH patients at risk for AF/AFL.