493 Prognostic value of myocardial scar and chamber enlargement at electroanatomical mapping during catheter ablation in adult congenital heart disease

Aims Atrial and ventricular tachyarrhythmias are common among patients with adult congenital heart disease (ACHD) and can impair quality of life and prognosis. Catheter ablation is often the main treatment option in this population, despite anatomical hurdles. Substrate mapping findings have not been thoroughly investigated as predictors of arrhythmia recurrence success and cardiovascular clinical outcome after ablation. We sought to determine the prognostic value of myocardial scar and chamber enlargement detected at electroanatomical mapping in ACHD patients undergoing catheter ablation of tachyarrhythmias. Methods and results Consecutive ACHD patients undergoing catheter ablation of atrial and ventricular tachycardias using different electroanatomical mapping systems were retrospectively identified from a hospital-based database. Scar extent detected at the electroanatomical mapping, as well as the total mapped area, was calculated. Arrhythmia recurrence, hospitalization for cardiovascular (CV) reasons, and a combined endpoint (arrhythmia recurrence and/or CV hospitalization) were evaluated during the follow-up. The relationship between the aforementioned electroanatomical findings and the patients’ outcome was assessed. Twenty patients (12 male, 60%; mean age 40 ± 11 years) undergoing atrial (n = 14; 70%) or ventricular (n = 6; 30%) tachyarrhythmia were included. Acute procedural success (arrhythmia termination and/or no reinduction) was achieved in all the patients. At a mean follow-up of 171 ± 135 weeks, eight patients (40%) had arrhythmia recurrence (4/6 in the ventricular tachycardia group, 67%, 4/14 in the atrial tachycardia group, 28%). Patients with arrhythmia recurrence had a more extensive bipolar scar (P = 0.029) and a larger total mapped area (P = 0.03) than patients without recurrence, and so did the patients with the composite endpoint (P = 0.029 and P = 0.03, respectively). Patients with subsequent CV hospitalization had a larger total mapped area than patients without CV hospitalization (P = 0.017). The presence of a bipolar scar ≥22.95 cm2 predicted arrhythmia relapse (0.039) at the multivariate analysis. Conclusions Patients with ACHD show a high recurrence rate after catheter ablation, especially for ventricular tachycardias. A large bipolar scar at the electroanatomical mapping and total mapped area predict arrhythmia recurrence, likely due to the presence of more extensive reentry circuits. A large total mapped area, which may reflect a greater disease severity, predicts both arrhythmia recurrence and CV hospitalizations. Early referral of ACHD patients for catheter ablation may be a sound strategy in order to perform the procedure in the setting of less advanced heart disease.

488 Candidacy for heart transplantation in adult congenital heart disease patients: a single-centre, retrospective, cohort study

Aims End-stage heart failure (HF) is the leading cause of death in adult congenital heart disease (ACHD) population. Heart transplantation (HTx) improves prognosis in ACHD end-stage HF but candidacy evaluation, referral pattern, and correct listing timing are not fully elucidated in this population. To evaluate factors associated to refusal from Htx in ACHD patients with end-stage HF referred for HTx evaluation. Methods and results This retrospective cohort study enrolled consecutive ACHD patients considered for HTx in our institution between 2014 and 2020 and patients undergone HTx between 2000 and 2013. Refusal from HTx served as primary study endpoint. Between 2014 and 2020, 46 ACHD patients were evaluated for HTx, 14 ACHD patients underwent HTx between 2001 and 2013. The main indication to HTx in patients with single ventricle physiology was Fontan failure, while in patients with systemic left ventricle and systemic right ventricle physiology, it was systemic ventricular dysfunction. We compared clinical, anatomical and demographic data of 41 patients accepted for transplantation with 15 patients refused after screening. Risk factors for refusal were: coexistence of multiple high risk features [odds ratio (OR): 3.6; 95% confidence interval (CI): 1.1–12.9; P 0.048]; anatomical factors (OR: 14.5; 95% CI: 3.1–68.4; P 0.001), out-of-centre ACHD/HTx program referral (OR: 5.3; 95% CI: 1.5 to 19.0; p 0.01). Survival in patients accepted for HTx was significantly higher than survival in patients declined from HTx with landmark comparison at 20, 40 and 60 months of 87%, 78%, and 72% vs. 70%, 59%, and 20%, respectively. HTx refusal identifies a high risk ACHD patient subgroup (hazard ratio for overall mortality: 3.1; 95% CI: 1.1–8.3; P 0.02). Conclusions In our study risk factors for refusal from HTx are adverse anatomical features, coexistence of multiple conventional HTx high risk factors and out-of-centre referral. ACHD patients refused from HTx present shorter time to death. Efforts to increase HTx candidacy and to reduce referral delay in tertiary centre are strongly necessary for this growing population.

Early Right Heart Chambers Reverse Remodeling in Patients Operated in Adulthood for Congenital Lesions Associated with Right Heart Chambers Enlargement

Background Progressive right heart chambers dilatation is frequent in the adult congenital heart disease (ACHD) population. We evaluated the immediate and mid-term response of right heart chambers to surgery performed in adulthood for lesions associated with right heart chambers enlargement. Methods Thirty-six adult patients with lesions associated with right heart chambers enlargement submitted to surgery were studied . We collected echocardiographic data of right ventricle (RV) mid-diameter, right atrial volume indexed, RV systolic pressure, and tricuspid annular plane systolic excursion (TAPSE) prior to surgery (T0), at 2 to 5 days (T1), and 3 to 6 months (T2) after surgery. Results At T1, we observed a significant decrease of RV mid-diameter (47.2 ± 8.4 vs. 39.6 ± 7.4 mm, P < .001), right atrial volume indexed (45.6 ± 26.6 vs. 27.2 ± 11 ml/m2, P < .001), and RV systolic pressure (39 ± 14.8 vs. 32.8 ± 11.3 mm Hg, P = .03). At T2, a further significant deviation in the rate of RV diameter (39.6 ± 7.4 vs. 34.5 ± 5.1 mm, P < .001), in RV systolic pressure (32.8 ± 11.3 vs. 25.3 ± 5 mm Hg, P = .03) and TAPSE (13.9 ± 3.2 vs. 15.8 ± 2.6 mm, P < .001) was observed. Conclusions Positive right heart chambers remodeling occurs as early as in the immediate post-operative period in most ACHD patients operated for lesions associated with right heart chambers enlargement.