Prognostic significance of peak oxygen consumption ≤ 10 ml/kg/min in heart failure: context vs. criteria

Abstract

Background: Both heart failure (HF) treatment and management may distort or enhance the predictive accuracy of low peak oxygen consumption (pVO2≤10 ml/kg/min), blurring the identification of specific patients in whom heart transplantation (HT) could make a clinical difference. The aim of this study was to re-evaluate the prognostic significance of pVO2≤10 ml/kg/min in systolic HF in light of changes in medical treatment and management.

Methods: Two-year outcomes were compared across the "millennium dawn" (MD) between two HF cohorts with pVO2≤10 ml/kg/min and gas exchange ratio>1.10: 116 patients were recorded between 1994 and 1999 (pre-MD: mean pVO2 8.6±1.1 ml/kg/min) and 90 between 2001 and 2008 (post-MD: mean pVO2 8.8±1.0 ml/kg/min). Cardiac-related death was considered an event and event censoring was interrupted at 24 months for surviving patients.

Results: Patients across the MD had the same age, NYHA class, left ventricular ejection fraction and pVO2 (pre-MD: mean pVO2 8.6±1.1; post-MD: mean pVO2 8.8±1.0 ml/kg/min: NS). Seventy-one patients (34%) died: 51 (44%) in the pre-MD and 20 (22%) in the post-MD group (p<0.01). The post-MD group showed a better mean 1-year (83% vs. 68%; χ(2)=5.17, p=0.0229) and 2-year survival (77% vs. 56%; χ(2)=8.87, p=0.0029) compared to pre-MD patients.

Conclusions: Two-year outcome of HF patients with pVO2≤10 ml/kg/min has significantly improved in the post-MD era, suggesting the HT indication should not rely on a single CPET parameter, rather on a multifactorial clinical approach.

Keywords: Heart failure; Low peak VO(2); Prognosis.