Heart failure prognosis over time: how the prognostic role of oxygen consumption and ventilatory efficiency during exercise has changed in the last 20 years

Abstract

Aims: Exercise-derived parameters, specifically peak exercise oxygen uptake (peak VO₂ ) and minute ventilation/carbon dioxide relationship slope (VE/VCO₂ slope), have a pivotal prognostic value in heart failure (HF). It is unknown how the prognostic threshold of peak VO₂ and VE/VCO₂ slope has changed over the last 20 years in parallel with HF prognosis improvement.

Methods and results: Data from 6083 HF patients (81% male, age 61 ± 13 years), enrolled in the MECKI score database between 1993 and 2015, were retrospectively analysed. By enrolment year, four groups were generated: group 1 1993-2000 (n = 440), group 2 2001-2005 (n = 1288), group 3 2006-2010 (n = 2368), and group 4 2011-2015 (n = 1987). We compared the 10-year survival of groups and analysed how the overall risk (cardiovascular death, urgent heart transplantation, or left ventricular assist device implantation) changed over time according to peak VO₂ and VE/VCO₂ slope and to major clinical and therapeutic variables. At 10 years, a progressively higher survival from group 1 to group 3 was observed, with no further improvement afterwards. A 20% risk for peak VO₂ 15 mL/min/kg (95% confidence interval 16-13), 9 (11-8), 4 (4-2) and 5 (7-4) was observed in group 1, 2, 3, and 4, respectively, while the VE/VCO₂ slope value for a 20% risk was 32 (37-29), 47 (51-43), 59 (64-55), and 57 (63-52), respectively.

Conclusions: Heart failure prognosis improved over time up to 2010 in a HF population followed by experienced centres. The peak VO₂ and VE/VCO₂ slope cut-offs identifying a definite risk progressively decreased and increased over time, respectively. The prognostic threshold of peak VO₂ and VE/VCO₂ slope must be updated whenever HF prognosis improves.

Keywords: Cardiopulmonary exercise test; Heart failure; Peak oxygen uptake; Prognosis; VE/VCO2 slope.