Frailty Assessment in Coronary Artery Bypass Grafting: A Review of Current Tools and Clinical Applications.

Frailty has emerged as a critical determinant of operative risk among patients undergoing coronary artery bypass grafting (CABG), particularly as the age and comorbidity burden of this population continue to rise. Unlike chronological age or traditional risk indices alone, frailty captures reduced physiologic reserve and vulnerability to surgical stress through phenotypic, functional, and cumulative deficit-based frameworks. In CABG populations, frailty has been consistently associated with increased operative mortality, postoperative morbidity, prolonged hospitalization, delirium, and non-home discharge. Despite its prognostic importance, no consensus exists regarding the optimal method for frailty assessment, and most outcome-focused studies rely on a single instrument without direct comparison across tools. This review examines the conceptual foundations, clinical feasibility, and associations with outcomes of frailty instruments applicable to CABG, including phenotypic, performance-based, cumulative deficit, clinician-rated, administrative, cardiac-specific, multidomain, functional, and biomarker-based approaches. These instruments differ substantially in domain coverage, resource requirements, feasibility, and predictive performance across clinical outcomes, and no single tool is universally optimal. Tool selection should therefore be guided by clinical context and the purpose of assessment, whether for risk stratification, perioperative counseling, preoperative optimization, or discharge planning. Frailty identification also provides actionable opportunities for intervention, including prehabilitation, nutritional support, anemia management, and early postoperative care planning. Further comparative research in CABG-specific cohorts is needed to define best practices for frailty assessment and its integration into perioperative cardiac surgical care.