['Pulmonary outflow tract obstruction (POTO) reduces systemic atrioventricular valve (SAVV) regurgitation severity in congenitally corrected transposition of the great arteries (ccTGA). Therefore, pulmonary artery banding is proposed as a palliative intervention. We aimed to investigate the effect of native or surgically induced POTO on event-free survival, defined as the composite of all-cause mortality, heart transplantation, or congestive heart failure (CHF).', 'Patients with ccTGA (n=62; median age 27.5 (IQR 18.4-39.4) years; 39% with POTO) were selected from the Adult Congenital Heart Disease database of a tertiary hospital. At first visit, SAVV regurgitation ≥ 3/4, systemic RV dysfunction ≥ moderate, and CHF were present in 26%, 26%, and 15% of patients, respectively. Over a mean follow-up time of 10.1 ± 6.1 years, all-cause mortality, rate of heart transplantation, and CHF were 18%, 8% and 40%, respectively. SAVV regurgitation (HR: 1.99; 95% CI: 1.01-3.92; P=0.048) and systemic RV dysfunction severity (HR: 1.89; 95% CI: 1.05-3.37; P=0.033) were associated with the composite endpoint, independently of age at baseline, POTO, Ebstein-like malformation, and systemic RV dilatation. Patients with POTO had lower risk for developing SAVV regurgitation ≥ 3/4 (HR: 0.18; 95% CI: 0.05-0.58; P=0.004) and moderate systemic RV dysfunction (HR: 0.34; 95% CI: 0.15-0.78; P=0.011). When POTO was present, the mean progression-free interval for the composite endpoint increased from 11.2 to 18.1 years (P=0.035).'] Does pulmonary outflow obstruction protect against heart failure in adults with congenitally corrected transposition of the great arteries?