BackgroundTranscatheter aortic valve implantation (TAVI) is preferred for treating severe aortic stenosis in older, frail populations, yet the impact of frailty on TAVI's economic and clinical outcomes is not well-studied. MethodsThis retrospective cohort study included 2,175 TAVI patients from 2015 to 2019 using Korea's National Health Insurance Service database, stratifying patients into low, intermediate, and high-frailty groups using the Hospital Frailty Risk Score (HFRS). Healthcare costs, admissions, and total length of hospitalization were analyzed using Wilcoxon-rank test 12 months pre- and post-TAVI. Composite endpoint of death, stroke, and major bleeding, with individual outcomes, were compared using Chi-squared tests and Kaplan-Meier analysis. ResultsMean age was 80.2 years, and 47.3% were male. 747 (34.3%) were low-frailty, 1,159 (53.3%) were moderate-frailty, and 269 (12.4%) were high-frailty. After TAVI, medical costs decreased in the intermediate (pre-TAVI: 2,269,000 KRW [1,668 USD], post-TAVI: 1,607,000 KRW [1,181 USD], p<0.001) and high frailty groups (pre-TAVI: 3,949,000 KRW [2,904 USD], post-TAVI: 2,188,000 KRW [1,609 USD], p<0.001). All frailty groups had shorter length of hospital stay post-TAVI (26 to 21 days in the low, 44 to 31 days in the intermediate, and 65 to 41 days in the high frailty group; all p<0.001). The composite outcome was higher in the frailer groups (27.8% in the low vs. 31.5% in the intermediate vs. and 37.9% in the high frailty group; p=0.008). All groups showed comparable rates of cardiovascular death, stroke or bleeding. ConclusionTAVI is clinically viable and cost-saving treatment option for frail patients with severe aortic stenosis.