Cardiorespiratory optimal point during exercise testing as a predictor of all-cause mortality.

Ramos PS, Araújo CG

Rev Port Cardiol. 2017 Apr;36(4):261-269. doi: 10.1016/j.repc.2016.09.017. Epub
2017 Mar 17

INTRODUCTION AND AIM: The cardiorespiratory optimal point (COP) is a novel index,
calculated as the minimum oxygen ventilatory equivalent (VE/VO2) obtained during
cardiopulmonary exercise testing (CPET). In this study we demonstrate the
prognostic value of COP both independently and in combination with maximum oxygen
consumption (VO2max) in community-dwelling adults.
METHODS: Maximal cycle ergometer CPET was performed in 3331 adults (66% men) aged
40-85 years, healthy (18%) or with chronic disease (81%). COP cut-off values of
<22, 22-30, and >30 were selected based on the log-rank test. Risk discrimination
was assessed using COP as an independent predictor and combined with VO2max.
RESULTS: Median follow-up was 6.4 years (7.1% mortality). Subjects with COP >30
demonstrated increased mortality compared to those with COP <22 (hazard ratio
[HR] 6.86, 95% confidence interval [CI] 3.69-12.75, p<0.001). Multivariate
analysis including gender, age, body mass index, and the forced expiratory volume
in 1 s/vital capacity ratio showed adjusted HR for COP >30 of 3.72 (95% CI
1.98-6.98; p<0.001) and for COP 22-30 of 2.15 (95% CI 1.15-4.03, p<0.001).
Combining COP and VO2max data further enhanced risk discrimination.
CONCLUSIONS: COP >30, either independently or in combination with low VO2max, is
a good predictor of all-cause mortality in community-dwelling adults (healthy or
with chronic disease). COP is a submaximal prognostic index that is simple to
obtain and adds to CPET assessment, especially for adults unable or unwilling to
achieve maximal exercise.