BackgroundAlthough the unique risks of implanting a prosthetic valve after aortic valve (AV) surgery in young patients are well established, studies of aortic root replacement (ARR) are lacking. We investigated long-term outcomes after valve-sparing root replacement (VSRR) versus the use of a composite valve graft with bioprosthesis (b-CVG) in patients age <50 years. MethodsA total of 543 patients age <50 years underwent VSRR (n = 335) or b-CVG (n = 208) between 2004 and 2021 from 2 aortic centers, excluding those with dissection or endocarditis. Endpoints included mortality over time, reoperative aortic valve replacement (AVR), and development of greater than moderate aortic insufficiency (AI) or aortic stenosis (AS). Fine and Gray competing risk regression was used to compare the risk of reintervention. Propensity score matching (PSM) balanced patient comorbidities, and landmark analysis isolated outcomes beginning 4 years postoperatively. ResultsCompared with VSRR, b-CVG was associated with lower 12-year survival (88.6% vs 92.9%; P = .036) and a higher rate of AV reintervention (37.6% vs 12.0%; P = .018). After PSM, survival was similar in the 2 arms (93.4% for b-CVG vs 93.0% for VSRR; P = .72). However, both Fine and Gray multivariable risk regression and PSM showed that b-CVG was independently associated with AV reintervention at >4 years postoperatively (Fine and Gray: subdistribution hazard ratio, 4.3 [95% confidence interval, 1.8-10.2; P = .001]; PSM: 35.7% for b-CVG versus 14.3% for VSRR; P = .024]). PSM rates of greater than moderate AI/AS at 10 years were more than 2-fold greater in the b-CVG arm compared with the VSRR arm (37.1% vs 15.9%; P = .571). Conclusionsb-CVG in young patients is associated with early valvular degeneration, with increasing rates of reoperative AVR occurring even within 10 years. In contrast, VSRR is durable with excellent survival. In eligible young patients, every effort should be made to retain the native AV.