This study, a secondary analysis of the MOSCA-FRAIL randomized clinical trial, aimed to assess the outcomes of invasive versus conservative treatment strategies in adults with frailty and non-ST-segment elevation myocardial infarction (NSTEMI). The MOSCA-FRAIL trial compared these strategies in 167 patients aged 70 years or older with frailty (Clinical Frailty Scale score ≥4) and NSTEMI. The extended follow-up period was extended to January 31, 2023, with data analysis conducted from April 5 to 29, 2023, using the intention-to-treat principle. The primary endpoint was the difference in restricted mean survival time (RMST) for all-cause death. Secondary endpoints included readmissions for any cause. The mean follow-up was 1113 days, with 93 deaths and 367 readmissions. The RMST for all-cause death was 3.13 years in the invasive group and 3.06 years in the conservative group, with inconclusive differences in survival time. However, patients in the invasive group tended to have shorter survival in the first year but more prolonged survival after the first year. Kaplan-Meier curves showed no significant differences in mortality between the two groups, but the curves intersected around 1 year, indicating a violation of the proportionality assumption. A landmark analysis starting from the first year showed that the invasive treatment improved survival after the first year. Subgroup analysis based on the Clinical Frailty Scale score revealed that invasive treatment reduced survival during the first year in patients with higher frailty (CFS >4) but had no significant effect in patients with lower frailty (CFS = 4). The study concluded that an initial invasive strategy did not improve midterm outcomes compared to a conservative approach in patients with frailty and NSTEMI. However, there was a time-dependent pattern in the distribution of deaths, with early harm followed by late benefit, particularly in patients with higher frailty. These findings suggest that an initial conservative strategy may be more appropriate for patients with NSTEMI and high levels of frailty.This study, a secondary analysis of the MOSCA-FRAIL randomized clinical trial, aimed to assess the outcomes of invasive versus conservative treatment strategies in adults with frailty and non-ST-segment elevation myocardial infarction (NSTEMI). The MOSCA-FRAIL trial compared these strategies in 167 patients aged 70 years or older with frailty (Clinical Frailty Scale score ≥4) and NSTEMI. The extended follow-up period was extended to January 31, 2023, with data analysis conducted from April 5 to 29, 2023, using the intention-to-treat principle. The primary endpoint was the difference in restricted mean survival time (RMST) for all-cause death. Secondary endpoints included readmissions for any cause. The mean follow-up was 1113 days, with 93 deaths and 367 readmissions. The RMST for all-cause death was 3.13 years in the invasive group and 3.06 years in the conservative group, with inconclusive differences in survival time. However, patients in the invasive group tended to have shorter survival in the first year but more prolonged survival after the first year. Kaplan-Meier curves showed no significant differences in mortality between the two groups, but the curves intersected around 1 year, indicating a violation of the proportionality assumption. A landmark analysis starting from the first year showed that the invasive treatment improved survival after the first year. Subgroup analysis based on the Clinical Frailty Scale score revealed that invasive treatment reduced survival during the first year in patients with higher frailty (CFS >4) but had no significant effect in patients with lower frailty (CFS = 4). The study concluded that an initial invasive strategy did not improve midterm outcomes compared to a conservative approach in patients with frailty and NSTEMI. However, there was a time-dependent pattern in the distribution of deaths, with early harm followed by late benefit, particularly in patients with higher frailty. These findings suggest that an initial conservative strategy may be more appropriate for patients with NSTEMI and high levels of frailty.