Impact of frailty on post-procedural adverse outcomes in older adults aged ≥75 years undergoing percutaneous coronary intervention: a systematic review of observational studies

Purpose The global aging population has led to a growing number of elderly patients aged ≥75 years undergoing percutaneous coronary intervention (PCI). Frailty is a common geriatric syndrome in this population, related to decreased physiological reserve and reduced ability to cope with stress, and it may significantly affect surgical outcomes. This systematic review aims to comprehensively evaluate the impact of frailty on major clinical outcomes (such as in-hospital mortality, all-cause mortality, bleeding, and stroke) in patients aged ≥75 years after percutaneous coronary intervention. Methods We systematically searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to December 2025. We included retrospective or prospective cohort studies reporting the relationship between frailty (assessed by any validated tool) and prognosis in elderly patients aged ≥75 years undergoing PCI. Data extraction covered study characteristics, population, age, CAD type, frailty assessment, and outcomes. The Newcastle–Ottawa Scale assessed bias risk. A fixed-effect model was used if I 2 < 50%; otherwise a random-effects model was used. Subgroup, meta-regression analysis and sensitivity analyses explored heterogeneity sources. Funnel plots assessed publication bias. The GRADE system rated evidence quality for each outcome. Results This systematic review included a total of 18 cohort studies, comprising 11 retrospective and 7 prospective studies, involving 2,038,546 patients. Our pooled analysis demonstrated that, compared with their non-frail counterparts, frail patients aged ≥75 years had a significantly higher risk of mortality and adverse outcomes following PCI. Specifically, frailty was closely associated with an increased risk of in-hospital death (RR = 3.16, 95% CI: 1.28–7.78) and all-cause death (RR = 2.51, 95% CI: 1.78–3.56). Furthermore, frailty significantly increased the incidence of complications, including the risk of bleeding (RR = 2.26, 95% CI: 1.54–3.31) and stroke (RR = 1.90, 95% CI: 1.86–1.94). The GRADE evidence certainty was low across all outcomes. Conclusion In patients aged ≥75 years undergoing PCI, frailty is associated with increased risks of in-hospital mortality, all-cause mortality, bleeding, and stroke. These findings support perioperative risk stratification, shared decision-making, and individualized management, though low GRADE evidence and uncertainty warrant caution.