Cardiovascular diseases are still the number one cause of death worldwide, despite significant advances in diagnosis and treatment over the last 50 years. Coronary artery bypass graft (CABG) surgery is an important treatment option for coronary heart disease. Cardiac rehabilitation (CR) programs are a planned multidisciplinary approach to supervise exercise and educate patients about coronary artery disease risk factors and disease management. Cardiac rehabilitation consists of 3 main phases: in-hospital period (phase 1); early post-discharge period (phase 2) and exercise training period (phase 3). Cardiac rehabilitation phase II (KRII) is a secondary prevention program designed to restore health following a cardiac event and reduce the risk of mortality and future cardiac events. It covers approximately 2-12 weeks after discharge. This is the period when patients are closely monitored. A gradual physical activity program is applied according to the results of the applied tests. Participation in KRII is known to reduce hospital readmissions and mortality. Referral to KRII following an acute cardiac event is a Class IA recommendation.

Outpatient CR programs are designed to reduce the deconditioning negative effects of medical and surgical interventions in cardiac patients and have well-accepted health and survival benefits. CR improves exercise capacity, quality of life, and long-term prognosis in patients with coronary artery disease. The beneficial effects of cardiac rehabilitation applied to patients after CABG surgery on exercise capacity, coronary risk factors and quality of life have been documented (PubMed identification (ID): 22064600). Positive benefits of postdischarge exercise training have been demonstrated (PubMed ID: 10961975), and it seems reasonable to begin exercise training immediately after CABG surgery (PubMed ID: 23851406). A recent multicenter study showed that patients who actively participated in an outpatient CR program after CABG surgery exhibited greater improvement in exercise capacity and better survival without cardiovascular events than those who did not participate in the CR program (PubMed ID: 32037378).

Prior to this, international guidelines did not recommend resistance training as part of the CR program immediately after CABG surgery, with the rationale that physical exertion causes pressure or stress in the sternal area and should therefore be avoided for at least 6 weeks and 3 months after surgery. However, results of a published meta-analysis (PubMed ID: 20482475) suggest that resistance training is an effective exercise program to improve 6-minute walking distance in individuals with chronic heart failure.

The goals of resistance training in older adults are to increase exercise and functional capacity, reduce activity limitation, and improve functionality in performing daily activity, thereby improving social reintegration and health-related quality of life. Resistance training in older adults may increase muscle strength and endurance and thus prevent age-related loss of skeletal muscle mass and strength as well as loss of bone mass. Strength and balance are closely related and are important in improving dynamic balance and increasing strength, which helps maintain activities of daily living and prevent frailty in very old adults. Studies have been conducted to evaluate the effects of combined aerobic and resistance training on the functional capacity of patients undergoing CABG surgery. Studies (PubMed ID: 19477380, PubMed ID: 19782265) showed that combined training caused a significant improvement in peak oxygen uptake in this patient population. While CR is recommended to begin as soon as possible after discharge, enrollment typically occurs several weeks after hospital discharge. This creates a gap in rehabilitative care. Reduced physiological reserve resulting from surgery, hospitalization, and the recovery period between discharge and CR may increase the risk of postoperative complications, readmission, and physical disability. It is known that a delay in starting CR prolongs recovery, increases dependency on family/caregivers, and especially those of working age are negatively affected. Additionally, any delay may reduce the benefits of KR.

Many patients rapidly lose muscle and bone mass during sedentary periods after sternotomy, increasing the risk of falls and prolonging recovery time. Accordingly, a number of preliminary studies have shown superior results when activity is started earlier after sternotomy. (PubMed ID: 26722187, PubMed ID: 28101566, PubMed ID: 29602750, PubMed ID: 31504913). A current study also proved that starting exercise training 2 weeks after sternotomy is effective and safe (PubMed ID: 35731506 ).With this study plan, we hypothesized that comprehensive cardiac rehabilitation in the early period after CABG would increase functional capacity. The aim of our study is to investigate the effectiveness of early (2nd week) phase 2 cardiac rehabilitation compared to usual care in patients undergoing CABG surgery, based on the primary outcome of functional capacity and secondary outcomes of quality of life, frailty, and body composition. This study will be an important study investigating the effects of phase 2 cardiac rehabilitation applied in the early period (2nd week) after CABG surgery on functional capacity, quality of life, fragility and body composition.