Effect of Outpatient Cardiac Rehabilitation Program on Parameters of Submaximal Cardiopulmonary Exercise Testing among Patients with Coronary Heart Disease

Background The effect of cardiac rehabilitation (CR) on submaximal cardiopulmonary exercise testing (CPET) parameters in patients with coronary heart disease (CHD) has not been fully elucidated. Aims To investigate the effect of outpatient cardiac rehabilitation program (CRP) on submaximal CPET parameters. Methods A total of 285 CHD patients were enrolled in the study. The CR group consisted of 229 patients who completed a 3-6 months outpatient CRP after acute myocardial infarction, percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). The CRP included both aerobic and resistance training. Each patient underwent CPET with leg cycle ergometry at the beginning and the end of CRP. Fifty-six patients who only received home program instruction were enrolled as the control group and received the same testing at baseline and follow-up. SF-36 was used to evaluate the quality of life of each subject. Results A total of 285 CHD patients were recruited (male/female 264/21; training/control 229/56; PCI/CABG 177/52). No significant between-group differences (CR versus control) were found at baseline in baseline characteristics, peak oxygen uptake ( O2 peak), oxygen uptake efficiency slope (OUES), oxygen uptake efficiency plateau (OUEP), and minute ventilation-carbon dioxide production relationship ( E/ CO2 slope). The CR group had significant increase in O2 peak (18.8±4.4 to 22.7±5.1 mL/kg/min, p<0.0001), OUES (1710±444 to 1908±496 L/min/log (L/min), p<0.0001), OUEP (35.1±5.0 to 36.7±4.8 mL/L, p<0.0001), and decrease in E/ CO2 slope (32.0±6.4 to 31.0±5.2, p=0.0007) after CRP. The changes of O2peak and OUES in CR group were significantly greater than that of the control group during follow-up (p<0.01). As for quality of life, the CR group had significantly greater improvements in physical functioning score (PFS),role-physical score (RPS),physical component summary score (PCS), and vitality score (VTS) then the control group (p<0.05). The CABG group had significantly greater improvements in OUES, OUEP, E/ CO2 slope, also in PFS,RPS,PCS, and bodily pain score (BPS) after CRP than the PCI group (p<0.05). O2 RCP (r = 0.846, p < 0.0001), O2 AT (r = 0.810, p < 0.0001), and OUES/BW (r = 0.769, p < 0.0001) correlated best with O2 peak/kg. Changes in O2 peak/kg correlated better with changes in O2 AT (r = 0.559, p < 0.0001), O2 RCP (r = 0.522, p < 0.0001), and OUES/BW (r = 0.483, p < 0.0001). OUES (r=0.33056, p<0.0001), OUEP (r=0.22486, p=0.0001) significantly correlated with PFS; OUES (PCS: r=0.23548, p<0.0001; RPS: r=0.14433, p=0.0147) also significantly correlated with PCS and RPS. Conclusions Exercise-based CRP significantly improves peak aerobic capacity as well as submaximal CPET parameters and quality of life among CHD patients. Submaximal parameters may be clinically useful for quantification of exercise performance and improvements after physical training in patients with CHD.