Purpose: To examine the clinical impact of cardiorespiratory fitness (CRF) and improvements in CRF after cardiac rehabilitation (CR) in heart failure (HF) patients for their risk of all-cause mortality and unplanned hospitalization. Secondly, to investigate possible factors associated with the absence of improvement in CRF after rehabilitation.
Methods: We included 155 HF patients receiving CR between October 2009 and January 2015. Patients performed an incremental bicycle test to assess CRF through peak oxygen uptake (VO2-peak) before and after CR-based supervised exercise training. Patients were classified as responders or non-responders based on pre-to-post CR changes in VO2-peak (>=6% and <6%, respectively). Cox proportional hazards models evaluated all-cause mortality and unplanned hospitalization during 5 years of follow-up. Patient characteristics, HF features and co-morbidities were used to predict changes in VO2-peak using logistic regression analysis.
Results: Seventy HF patients (45%) were classified as responder. Non-responders had a significantly higher risk of all-cause mortality or hospitalization (HR = 2.15, 95% CI = 1.17-3.94) compared to responders. This was even higher in non-responders with low CRF at baseline (HR = 4.88, 95% CI = 1.71-13.93). Factors associated with non-response to CR were age (OR = 1.07/year, 95% CI = 1.03-1.11), baseline VO2-peak (OR = 1.16/ml/min/kg, 95% CI = 1.06-1.26) and adherence to CR (OR = 0.98/percentage, 95% CI = 0.96-0.998).
Conclusion: Independent from baseline CRF, the inability to improve VO2-peak by CR doubled the risk of death or unplanned hospitalization. The combination of lower baseline CRF and non-response was associated with even poorer clinical outcomes. Especially older HF patients with higher baseline VO2-peak and lower adherence have a higher probability of becoming a non-responder.
(C) 2017 American College of Sports Medicine