Frailty assessment and individualized exercise prescription in cardiac rehabilitation: current evidence and future directions

Frailty is an increasingly important clinical consideration in cardiac rehabilitation (CR), particularly among older adults and patients with heart failure, coronary artery disease, valvular disorders, and multiple chronic conditions. It is characterized by reduced physiological reserve and increased vulnerability to adverse outcomes following relatively minor physical or psychological stressors. Frail cardiac patients may experience muscle weakness, slow gait, impaired balance, fatigue, reduced exercise tolerance, nutritional deficiencies, cognitive difficulties, and limitations in activities of daily living. These factors can affect rehabilitation participation, exercise tolerance, adherence, and long-term functional recovery. Traditional cardiac rehabilitation programmes have primarily emphasized aerobic conditioning, cardiovascular risk-factor management, and general exercise capacity. However, these approaches may not adequately address the multidimensional impairments associated with frailty. Contemporary rehabilitation therefore requires systematic frailty screening, comprehensive functional assessment, and individualized exercise prescription based on the patient's dominant limitations, clinical stability, comorbidities, and personal goals. Validated instruments such as the Fried Frailty Phenotype, Clinical Frailty Scale, Edmonton Frail Scale, FRAIL questionnaire, Frailty Index, and Short Physical Performance Battery can support identification and monitoring of frailty. Exercise interventions for frail cardiac patients should generally combine progressive resistance training, aerobic conditioning, balance activities, functional mobility exercises, and flexibility training, with nutritional and psychosocial support when indicated. Evidence from the REHAB-HF trial and recent systematic reviews suggests that multidomain rehabilitation can improve physical function and frailty-related outcomes in selected patients with cardiovascular disease. A 2024 systematic review found that frailty is common among CR participants and that frailty status can improve following programme participation, although considerable variation exists in assessment tools and intervention design. More recent European guidance explicitly recommends offering CR to eligible patients with frailty rather than withholding rehabilitation because of frailty or comorbidities. This review examines the concepts and mechanisms of frailty, clinical assessment methods, and evidence for exercise-based interventions, individualized prescription strategies, safety considerations, multidisciplinary care, implementation barriers, and future research priorities. It proposes a practical framework for integrating frailty assessment into routine cardiac rehabilitation and translating assessment findings into progressive, patient-centred exercise programmes.