['This study sought to predict the value of tumor marker carbohydrate antigen 125 (CA125) before and after transcatheter aortic valve implantation (TAVI) for all-cause death and a composite endpoint of death, admission for heart failure, myocardial infarction, and stroke (major adverse cardiac events [MACE]).', 'Risk stratification after TAVI remains challenging. The use of biomarkers in this setting represents an unmet need.', 'CA125 was measured in 228 patients before and after TAVI. The association with outcomes was assessed using parametric Cox regression and joint modeling for baseline and longitudinal analyses, respectively. CA125 was evaluated as logarithm transformation and dichotomized by its median value (M1 ≤15.7 U/ml vs. M2 >15.7 U/ml).', 'At a median follow-up of 183 days (interquartile range: 63 to 365) and 144 days (interquartile range: 56 to 365), 50 patients (22%) died and 75 patients (33%) experienced MACE. A 3-fold increase in the rates for death and MACE was observed in patients above the median (M2 vs. M1) of CA125 (5.2 vs. 1.6 per 10 person-years and 8.3 vs. 3.3 per 10 person-years, respectively; p for both <0.001). In a multivariable analysis adjusted for logistic EuroSCORE, New York Heart Association functional class III/IV, and device success, baseline values of CA125 (M2 vs. M1) independently predicted death (hazard ratio [HR]: 2.18; 95% confidence interval [CI]: 1.11 to 4.26; p = 0.023) and MACE (HR: 1.77; 95% CI: 1.05 to 2.98; p = 0.031). In the longitudinal analysis, lnCA125 as a time-varying exposure, was highly associated with both endpoints: HR: 1.47; 95% CI: 1.01 to 2.14; p = 0.043 and HR: 2.26; 95% CI: 1.28 to 3.98; p = 0.005, for death and MACE, respectively.'] Does tumor marker carbohydrate antigen 125 predict adverse outcome after transcatheter aortic valve implantation?