Effects of routine invasive management on reinfarction risk in older adults with frailty and non-ST-segment elevation myocardial infarction: a subanalysis of a randomised clinical trial.

Background: Clinical trials and meta-analyses indicate a reduced reinfarction risk with invasive management in older patients with non-ST-segment elevation myocardial infarction (NSTEMI). This study investigated whether similar benefits might be observed in frail patients.

Methods: The coMOrbilidades Síndrome Coronario Agudo - FRAIL (MOSCA-FRAIL) trial included 167 adults aged ≥70 years with frailty (Clinical Frailty Scale ≥4 points) and NSTEMI, who were randomised to invasive (n=84) or conservative (n=83) strategy during the index hospitalisation. The primary end point of this subanalysis was reinfarction, considering all-cause mortality as a competing event, at a 3-year median follow-up. The time to first reinfarction and all reinfarctions (first and recurrent) were considered. The substudy was not prespecified.

Results: The total number of deaths (93, 56%) exceeded that of first reinfarctions (32, 19%). Invasive treatment did not influence the reinfarction risk when accounting for death as a competing risk (subdistribution HR=0.87, 95% CI 0.54 to 1.40, p=0.56). An initially increased mortality risk with invasive management (significant between days 131 and 175) shifted to a lower mortality risk over time. A total of 45 reinfarctions (first and recurrent) were observed. The longitudinal trajectories corroborated that the invasive strategy did not reduce the risk of reinfarction over time (p=0.72). However, mortality followed a biphasic pattern, with higher mortality in the invasive group during the first 6 months and a reduction between 9 months and 3 years (p=0.05 for the entire time-dependent trajectory). The win ratio for the invasive strategy versus the conservative strategy was 1.08 (95% CI 0.72 to 1.63, p=0.70).

Conclusions: In older adults with frailty and NSTEMI, routine invasive management did not reduce the reinfarction risk at a 3-year follow-up. The high all-cause mortality associated with frailty may limit the impact of invasive management. Due to the limited sample size and risk for type II error, these findings should be considered hypothesis-generating.

Trial registration number: NCT03208153.