Cardiorespiratory optimal point during exercise testing as a predictor of all-cause mortality.
OBJECTIVE
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.
Maternity Hospital Therezinha de Jesus, Faculty of Medical and Health Sciences - SUPREMA, Juiz de Fora, MG, Brazil.
Plínio S
PS
Ramos
Exercise Medicine Clinic - CLINIMEX, Rio de Janeiro, RJ, Brazil; Heart Institute Edson Saad, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. Electronic address: cgaraujo@iis.com.br.
Claudio Gil S
CG
Araújo
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies
Cardiopulmonary exercise testing; Consumo de oxigênio; Exercise; Exercício; Oxygen uptake; Teste cardiopulmonar de exercício; Ventilation; Ventilação