Background: Coronary artery bypass graft (CABG) surgery is known to induce significant muscle wasting. It remains to be investigated whether muscle wasting after CABG surgery relates to a worse clinical status at entry of rehabilitation and exercise-based rehabilitation remediates such muscle wasting.Design: Prospective observational study. Methods:In 21 males, changes in lean tissue mass (LTM) after CABG surgery were assessed and during a 12-week endurance exercise-based rehabilitation intervention. Changes in blood parameters and cardiopulmonary exercise capcity were assessed, and relations with changes in LTM were analyzed.Results: LTM decreased by -1.9±2.5kg (p<0.05) within 3 weeks after CABG surgery: greater LTM loss related to a lower ventilatory threshold at entry of rehabilitation (r=0.58-0.61, p<0.05). LTM was fully restored (+2.1±2.4kg, p<0.05) during rehabilitation. Conclusion:In males, CABG-induced LTM reduction was associated with a worse aerobic exercise tolerance at entry of rehabilitation, but this LTM reduction was fully remediated by endurance exercise-based rehabilitation.

New Findings What is the central question of this study?How does surgical aortic valve replacement affect cardiopulmonary and muscle function during exercise? What is the main finding and its importance?Early after the surgical replacement of the aortic valve a significant decline in pulmonary function was observed, which was followed by a decline in skeletal muscle function in the subsequent weeks of recovery. These date reiterate, despite restoration of aortic valve function, the need for a tailored rehabilitation programme for the respiratory and peripheral muscular system. Abstract Suboptimal post‐operative improvements in functional capacity are often observed after minimally invasive aortic valve replacement (mini‐AVR). It remains to be studied how AVR affects the cardiopulmonary and skeletal muscle function during exercise to explain these clinical observations and to provide a basis for improved/tailored post‐operative rehabilitation. Twenty‐two patients with severe aortic stenosis (AS) (aortic valve area (AVA) <1.0 cm²) were pre‐operatively compared to 22 healthy controls during submaximal constant‐workload endurance‐type exercise for oxygen uptake (V̇normalO2), carbon dioxide output (V̇normalCO2), respiratory gas exchange ratio, expiratory volume (V̇E), ventilatory equivalents for O2 (V̇E/V̇normalO2) and CO2 (V̇E/V̇normalCO2), respiratory rate (RR), tidal volume (Vt), heart rate (HR), oxygen pulse (V̇normalO2/HR), blood lactate, Borg ratings of perceived exertion (RPE) and exercise‐onset V̇normalO2 kinetics. These exercise tests were repeated at 5 and 21 days after AVR surgery (n = 14), along with echocardiographic examinations. Respiratory exchange ratio and ventilatory equivalents (V̇E/V̇normalO2 and V̇E/V̇normalCO2) were significantly elevated, V̇normalO2 and V̇normalO2/HR were significantly lowered, and exercise‐onset V̇normalO2 kinetics were significantly slower in AS patients vs. healthy controls (P < 0.05). Although the AVA was restored by mini‐AVR in AS patients, V̇E/V̇normalO2 and V̇E/V̇normalCO2 further worsened significantly within 5 days after surgery, accompanied by elevations in Borg RPE, V̇E and RR, and lowered Vt. At 21 days after mini‐AVR, exercise‐onset V̇normalO2 kinetics further slowed significantly (P < 0.05). A decline in pulmonary function was observed early after mini‐AVR surgery, which was followed by a decline in skeletal muscle function in the subsequent weeks of recovery. Therefore, a tailored rehabilitation programme should include training modalities for the respiratory and peripheral muscular system.