Objectives Despite evidence, frailty is not routinely assessed before cardiac surgery. We compared five brief frailty tests for predicting poor outcomes after aortic valve replacement and evaluated a strategy of performing comprehensive geriatric assessment (CGA) in screen‐positive patients. Design Prospective cohort study. Setting A single academic center. Participants Patients undergoing surgical aortic valve replacement (SAVR) (n = 91; mean age = 77.8 y) or transcatheter aortic valve replacement (TAVR) (n = 137; mean age = 84.5 y) from February 2014 to June 2017. Measurements Brief frailty tests (Fatigue, Resistance, Ambulation, Illness, and Loss of weight [FRAIL] scale; Clinical Frailty Scale; grip strength; gait speed; and chair rise) and a deficit‐accumulation frailty index based on CGA (CGA‐FI) were measured at baseline. A composite of death or functional decline and severe symptoms at 6 months was assessed. Results The outcome occurred in 8.8% (n = 8) after SAVR and 24.8% (n = 34) after TAVR. The chair rise test showed the highest discrimination in the SAVR (C statistic = .76) and TAVR cohorts (C statistic = .63). When the chair rise test was chosen as a screening test (≥17 s for SAVR and ≥23 s for TAVR), the incidence of outcome for screen‐negative patients, screen‐positive patients with CGA‐FI of .34 or lower, and screen‐positive patients with CGA‐FI higher than .34 were 1.9% (n = 1/54), 5.3% (n = 1/19), and 33.3% (n = 6/18) after SAVR, respectively, and 15.0% (n = 9/60), 14.3% (n = 3/21), and 38.3% (n = 22/56) after TAVR, respectively. Compared with routinely performing CGA, targeting CGA to screen‐positive patients would result in 54 fewer CGAs, without compromising sensitivity (routine vs targeted: .75 vs .75; P = 1.00) and specificity (.84 vs .86; P = 1.00) in the SAVR cohort; and 60 fewer CGAs with lower sensitivity (.82 vs.65; P = .03) and higher specificity (.50 vs .67; P < .01) in the TAVR cohort. Conclusions The chair rise test with targeted CGA may be a practical strategy to identify older patients at high risk for mortality and poor recovery after SAVR and TAVR in whom individualized care management should be considered. J Am Geriatr Soc 67:2031–2037, 2019