BackgroundTranscatheter aortic valve implantation (TAVI) is preferred for treating severe aortic stenosis in older, frail populations, yet the impact of frailty on economic and clinical outcomes of TAVI is not well studied. MethodsThis retrospective cohort study included 2175 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). Health care 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 χ2 tests and Kaplan-Meier analysis. ResultsMean age was 80.2 years, and 47.3% were male; 747 (34.3%) were low frailty, 1159 (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 [$1668 USD], post-TAVI: 1,607,000 KRW [$1181 USD]; P < 0.001) and high-frailty groups (pre-TAVI: 3,949,000 KRW [$2904 USD], post-TAVI: 2,188,000 KRW [$1609 USD]; P < 0.001). All frailty groups had shorter length of hospital stay post-TAVI (26 to 21 days in the low-frailty, 44 to 31 days in the intermediate-frailty, 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-frailty vs 31.5% in the intermediate-frailty vs 37.9% in the high-frailty group; P = 0.008). All groups showed comparable rates of cardiovascular death, stroke, or bleeding. ConclusionsTAVI is clinically viable and cost-saving treatment option for frail patients with severe aortic stenosis.