Atrial Arrhythmia in Patients with Tetralogy of Fallot and Pulmonary Atresia with Intact Ventricular Septum: Risk of Thromboembolism and Bleeding

IntroductionAdults with congenital heart disease (CHD), particularly tetralogy of Fallot (ToF) and pulmonary atresia with intact ventricular septum (PA-IVS), are at increased risk for atrial fibrillation (AF) and its complications. We evaluated thromboembolic and bleeding risks in this population and assessed the predictive value of CHA2DS2-VASc and HAS-BLED scores. MethodsIn this retrospective cohort study, patients with ToF-PS, ToF-PA, or PA-IVS and AF were identified across Mayo Clinic sites (1999-2023) were analyzed. Primary outcomes were thromboembolism (stroke, TIA, systemic embolism) and major bleeding. Cox regression controlled for age; anticoagulation exposure was treated as time-varying. Risk score performance was evaluated using ROC curves. Results300 patients with ToF-PS, ToF-PA, or PA-IVS were identified. Over 2,296 person-years, 12 thromboembolic events occurred (5.23/1000 person-years). Prior stroke, TIA, peripheral embolism, and Potts shunt were significant predictors. CHA2DS2-VASc had good discrimination (c-statistic 0.78); no events occurred in patients with a score of 0. Major bleeding occurred 69 times over 1,845 person-years (3.74/100 person-years), more frequently in ToF-PA (HR 2.05, p = 0.005), chronic AF, and those with Waterson shunts (HR 4.64, p = 0.013). DOAC use was associated with significantly higher bleeding risk than warfarin (HR 5.89, p < 0.001). The HAS-BLED score had limited predictive value (c-statistic 0.59) (figure 1). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/25328122v1_fig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@ef29e7org.highwire.dtl.DTLVardef@1a83597org.highwire.dtl.DTLVardef@5658a3org.highwire.dtl.DTLVardef@d547f8_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Graphical Abstract C_FIG DiscussionIn CHD patients with AF, thromboembolic risk was low with anticoagulation, and CHA2DS2-VASc performed well. However, bleeding risk, particularly with DOACs and in patients with specific anatomical features, was high. Warfarin may be the safer anticoagulant in this population.