Objective: The response of the RV following treatment of aortic stenosis is poorly defined, reflecting the challenge of accurate RV assessment. Cardiovascular magnetic resonance (CMR) is the established reference for imaging of RV volumes, mass and function. We sought to define the impact of transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) upon RV function in patients treated for severe aortic stenosis using CMR. Methods: A 1.5T CMR scan was performed preoperatively and 6 months postoperatively in 112 (56 TAVI, 56 SAVR; 76 ± 8 years) high-risk severe symptomatic aortic stenosis patients across two UK cardiothoracic centres. Results: TAVI patients were older (80.4 ± 6.7 vs. 72.8 ± 7.2 years, p < 0.05) with a higher STS score (2.13 ± 0.73 vs. 5.54 ± 3.41%, p < 0.001). At 6 months, SAVR was associated with a significant increase in RV end systolic volume (33 ± 10 vs. 37 ± 10 ml/m2, p = 0.008), and decrease in RV ejection fraction (58 ± 8 vs. 53 ± 8%, p = 0.005) and tricuspid annular plane systolic excursion (22 ± 5 vs. 14 ± 3 mm, p < 0.001). Only 4 (7%) SAVR patients had new RV late gadolinium hyper-enhancement with no new cases seen in the TAVI patients at 6 months. Longer surgical cross-clamp time was the only predictor of increased RV end systolic volume at 6 months. Post-TAVI, there was no observed change in RV volumes or function. Over a maximum 6.3 year follow-up, 18(32%) of TAVI patients and 1(1.7%) of SAVR patients had died (p = 0.001). On multivariable Cox analysis, the RV mass at 6 m post-TAVI was independently associated with all-cause mortality (HR 1.359, 95% CI 1.108–1.666, p = 0.003). Conclusions: SAVR results in a deterioration in RV systolic volumes and function associated with longer cross-clamp times and is not fully explained by suboptimal RV protection during cardiopulmonary bypass. TAVI had no adverse impact upon RV volumes or function.