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

BackgroundThe 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. MethodsIn 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 Harrells 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. ResultsIn 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 [&ge;]5.4 cm for increased hazards of incident AF/AFL. ConclusionLower 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.