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

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.