Introduction:
Peak oxygen uptake (VO
2peak
), as determined by cardiopulmonary exercise testing (CPET), is informative of cardiovascular fitness and heart failure (HF) disease progression. Due to their clinical meaningfulness, many patients with HF undergo multiple CPETs throughout their lifetimes. However, a gap in knowledge exists regarding the prognostic value of longitudinal changes in VO
2peak
for mortality risk. The aim of this study was to investigate whether VO
2peak
trajectories are predictive of mortality among patients with HF.
Methods:
Patients with HF who completed two CPETs (separated by at least 3 months, mean = 25.3 months) at Washington University School of Medicine between May 1993 and February 2020 were included in the study. Vital statuses and mortality dates were collected from May 2019 to May 2020 via electronic health records and the Social Security Death Index. Kaplan-Meier and Cox proportional hazards regression analyses were used to evaluate associations between changes in VO
2peak
and mortality.
Results:
The sample included 162 patients with a mean age of 48.5 years (SD 10.5) at baseline. VO
2peak
averaged 18.1 (SD 4.9) ml·kg
-1
·min
-1
in 121 men and 15.1 (SD 4.1) ml·kg
-1
·min
-1
in 41 women. During a median follow-up of 11.8 years (range 1-23 years), 70 patients died. A significant negative association between VO
2peak
and mortality was observed (hazard ratio [HR] = 0.92; 95% Confidence Interval [CI] = 0.87 to 0.98; P = 0.011). Patients whose VO
2peak
increased from their baseline to second CPET had higher survival rates compared to patients whose VO
2peak
decreased. Moreover, the annual rate of change in VO
2peak
was associated with mortality rates. A 9% lower mortality rate was observed for each unit increase in VO
2peak
change (i.e., 1 ml·kg
-1
·min
-1
) for the entire follow-up period (HR = 0.91; 95% CI = 0.85 to 0.97) and at 10-year follow-up (HR = 0.91; 95% CI = 0.85 to 0.98), while a 12% lower mortality rate was observed at 5-year follow-up (HR = 0.88, 95% CI = 0.78 to 1.00) relative to baseline CPETs.
Conclusion:
Increases in VO
2peak
were associated with increased survival rate among patients with HF. These findings highlight the importance of promoting exercise and cardiac rehabilitation for patients with HF.
The discriminant prognostic value of adding exercise myocardial SPECT imaging to peak oxygen uptake (MVO2) in congestive heart failure patients