Background: Children with Shone's Complex (SC) have multiple levels of left heart obstruction and often require a number of left heart interventions. They are at risk of long-term morbidity and mortality. However, long-term outcomes in children with SC are limited. Methods: SC was defined as a mitral valve (MV) anomaly and ≥ 1 other left heart obstructive lesion including coarctation of the aorta (CoA), subvalvar, supravalvar and aortic valvar stenosis (AS). MV morphology type was classified as typical (MVtyp) - hypoplastic annulus, thickened leaflets; mitral ring (MVr); arcade or other papillary muscle anomaly (MVarc); parachute (MVpap); and other including double-orifice (MVo). Pts who underwent Norwood palliation were excluded. We reviewed overall outcomes and focused on the impact of pulmonary hypertension (PH) and pre-existing atrial septal defect (ASD) on left heart growth, number of interventions, and death/transplant (OHT). Results: A total of 129 SC pts presented at 35d (0d - 18yrs) of age and were followed for 7.0 ± 6.8 years. MV morphology included MVtyp (n=89, 68%), MVr (n=23, 18%), MVpap (n=21, 16%), MVarc (n=25, 19%). A total of 113 pts underwent 232 (median 2, 0-5) interventions including ASD closure (n=49), VSD closure (n=30), AVR (n=8), MVR (n=10), MV repair (n=39), AS repair (n=37), balloon valvuloplasty (n=36) and CoA dilation/repair (n=60). Pre-intervention, ASD was associated with lower mean LA pressure 11.7±5.6 vs 18.5±6.5 mmHg (p=0.02) and lower mitral gradient 5.3 ± 5.6 vs 10.9 ± 10.6 mmHg (p<0.01) on catheterization. Following first surgical intervention, residual ASD was associated with decreased annular growth of AV (p=0.042) and MV (p=0.01), smaller increase in LVEDD (p=0.001) and LVESD (p=0.018). MVpap was associated with smaller MV (p<0.001) and less MV annular growth by latest follow-up (p=0.001). Twenty-year OHT-free survival was 87%. By multivariate analysis, PH was associated with death/OHT (OR 6.8, 1.7-27.8). Survival in pts without residual ASD was 88% vs 77% with an ASD (p=0.017). Conclusions: SC pts with residual ASD have a higher rate of interventions. Left heart growth is optimized with ASD closure, while MVpap is associated with decreased growth. Pts who develop PH and have residual ASDs are at higher risk of mortality.