Pick your threshold: a comparison among different methods of anaerobic threshold evaluation in heart failure prognostic assessment.

Salvioni E; Mapelli M; Bonomi A; Magrì D; Piepoli M; Frigerio M; Paolillo S; Corrà U; Raimondo R; Lagioia R; Badagliacca R; Filardi PP; Senni M; Correale M; Cicoira M; Perna E; Metra M; Guazzi M; Limongelli G; Sinagra G; Parati G; Cattadori G; Bandera F; Bussotti M; Vignati C; Lombardi C; Scardovi AB; Sciomer S; Passantino A; Emdin M; Passino C; Santolamazza C; Girola D; Zaffalon D; De Martino F; Agostoni P;

Chest [Chest] 2022 Jun 23.
Date of Electronic Publication: 2022 Jun 23.

Background: In clinical practice, anaerobic threshold (AT), is used to guide training and rehabilitation programs, to define risk of major thoracic or abdominal surgery, and to assess prognosis in heart failure (HF). VO 2 AT has been reported as absolute value (VO 2 ATabs), as percentage of predicted peak VO 2 (VO 2 AT%peak_pred) or as percentage of observed peak VO 2 value (VO 2 AT%peak_obs). A direct comparison of the prognostic power among these different ways to report AT is missing.
Research Question: What is the prognostic power of these different ways to report AT?
Study Design and Methods: Observational cohort study. We screened data of 7746 HF patients with history of reduced ejection fraction (<40%), recruited between 1998 and 2020 and enrolled in the MECKI register. All patients underwent a maximal cardiopulmonary exercise test (CPET), executed using a ramp protocol on an electronically braked cycle ergometer.
Results: In this study we considered 6157HF patients with identified AT. Follow up was 4.2 years (1.9-5.0). Both VO 2 ATabs (823(305 mL/min)) and VO 2 AT%peak&#95;pred (39.6(13.9%)) but not VO 2 AT%peak&#95;obs (69.2(17.7%)) well stratified the population as regards prognosis (composite endpoint: cardiovascular death, urgent heart transplant or left ventricular assist device). Comparing AUC values, VO 2 ATabs (0.680) and VO 2 AT%peak&#95;pred (0.688) performed similarly, while VO 2 AT%peak&#95;obs (0.538) was significantly weaker (P<0.001). Moreover, VO 2 AT%peak&#95;pred AUC value was the only performing as well as AUC based on peakVO 2 (0.710), with even a higher AUC (0.637 vs. 0.618 respectively) in the group with severe HF (peakVO 2 <12mL/min/kg). Finally, the combination of VO 2 AT%peak&#95;pred with Peak VO 2 and VE/VCO 2 shows the highest prognostic power.
Interpretation: In HF, VO 2 AT%peak&#95;pred is the best way to report VO 2 at AT in relation to prognosis, with a prognostic power comparable to that of peak VO 2 and, remarkably, in severe HF patients.