Factors Associated With Improved Exercise Tolerance Among Patients Undergoing Long-Term Phase III Cardiac...

This study aimed to clarify the characteristics of those who improved their exercise tolerance during a long-term cardiac rehabilitation (CR) program.

Our participants comprised patients with cardiovascular disease who participated in Phase II and Phase III outpatient CR programs at two facilities and underwent cardiopulmonary exercise testing at three timepoints (i.e., the start of Phase II, the end of Phase II, and 6 months after the completion of Phase III). Statistical analysis was conducted by dividing the patients into responders and non-responders according to whether or not improvement in peak oxygen uptake (VO₂) occurred from the end of Phase II to 6 months after the end of Phase III. A modified Poisson regression analysis was used with responders (1) and non-responders (0) as dependent variables and background factors, physical function, and exercise tolerance as independent variables, while adjusting for sex and age. A linear mixed-effects model was used to analyze the changes in exercise tolerance among non-responders and responders across the three timepoints.

A total of 124 participants (86 non-responders and 38 responders; median age, 71.5 years; and 92 men) were included in the analysis. Modified Poisson regression analysis indicated significant relationships between improvement in peak VO₂ and %Δpeak VO₂ (IRR: 0.981, 95% CI: 0.966-0.996) and %Δ ΔVO₂/ΔWR (IRR: 0.988, 95% CI: 0.978-0.998). Responders had a significantly lower peak VO₂ at the end of Phase II (estimate: -1.810 and p = 0.004) and a significantly higher peak VO₂ at the 6-month follow-up of Phase III (estimate: 3.961 and p < 0.001) than did non-responders.

Our results revealed that those who showed improvements in peak VO₂ during long-term outpatient CR were confirmed to be those with little improvement in peak VO₂ and ΔVO₂/ΔWR during the Phase II outpatient CR program.