Objective: The prevalence of heart failure (HF) among adult patients with congenital heart disease (ACHD) is rising. Right ventricle (RV) exercise reserve and its relationship to outcomes have not been characterised. We aim to evaluate the prognostic impact of impaired RV reserve in an ACHD population referred for cardiopulmonary exercise testing (CPET). Methods: This retrospective study evaluates patients with ACHD who underwent CPET (n=147) with first-pass radionuclide ventriculography at a single tertiary care centre. RV reserve was categorised as normal, mild to moderately or severely impaired. The primary composite clinical outcome included clinical right HF, arrhythmia, transplantation or death. Results: Patients were median age 41±13 years, 50% were female and median follow-up was 1.1 (IQR: 0.7–2.0) years. Exercise RV reserve was impaired in 103 patients (70%), of whom 32% were asymptomatic. Resting RV systolic function poorly predicted RV reserve, with 52% of patients with severe impairment having a qualitatively normal echocardiographic assessment. The severely impaired reserve group had lower peak oxygen consumption (VO₂)(17.2 vs 22.5 mL/kg/min, p<0.0001) compared with the normal reserve group, and was more likely to develop the composite outcome (48% vs 9%, log-rank p<0.001). Severely impaired RV reserve predicted event-free survival after adjusting for peak VO₂, age, sex, RV pathology, QRS duration, New York Heart Association class, resting RV ejection fraction and RV dilation by echocardiography or MRI (HR 3.7, 95% CI 1.1 to 13.0, p=0.039). Conclusion: Impaired RV reserve, occurred in asymptomatic patients, was not well predicted by resting systolic function assessment, and strongly predicted adverse cardiovascular outcomes.

The impact of implant depth of the Abbott Navitor intra-annular, self-expanding valve on redo-transcatheter aortic valve replacement (TAVR) feasibility is unknown. The authors sought to determine the feasibility of redo-TAVR and coronary access with Edwards Sapien 3 (S3) valve after initial Navitor valve, based on various implant depths on computed tomography (CT) simulation. Using 2050 pre-TAVR CTs of patients with native aortic stenosis, initial Navitor TAVR simulations were done at 3 implant depths (0 mm, 3 mm, and 5 mm), with frame expansion assumed at native annular dimensions and commissural alignment not achievable. Redo-TAVR with S3 was deemed unfeasible based on valve-to-sinotubular junction and/or valve-to-sinus height distances <2 mm, while the neoskirt height of the S3 valve based on target implant depth determined coronary access feasibility. Redo-TAVR was deemed the least unfeasible in 2.3% of patients with initial Navitor implant depth at 3 mm and redo-S3 implanted lower at Node 2 vs 40.5% of patients with initial Navitor depth at 3 mm and redo-S3 implanted higher at Node 3 (P < 0.0001). Similarly, coronary access was the least challenging with initial Navitor depth at 3 mm and redo-S3 implanted lower at Node 2 (P < 0.0001). These results were similar across all Navitor valve sizes. Commissural alignment in Navitor improved redo-TAVR feasibility only when implanted at 5 mm. In our CT simulation study, redo-TAVR and coronary access were predicted to be the most favorable with initial Navitor implant depth of 3 mm and redo-S3 implanted lower at Node 2. In vivo analysis will help confirm these findings.