Peak oxygen consumption and prognosis in heart failure: 14 mL/kg/min is not a "gender-neutral" reference.

Background: Peak oxygen consumption (VO2) predictive authority in heart failure (HF) has been established from male cohorts. We evaluated the gender impact on the prognostic meaning of low peak VO2.

Methods: We followed 529 HF patients (116 female), with peak VO2 ≤ 14 mL/kg/min, until cardiovascular death (CVD) and urgent heart transplantation.

Results: During follow up, 156 (29%) patients had cardiac events. Female gender, age, left ventricular ejection fraction, peak VO2, peak systolic blood pressure, and beta-blocker treatment all contributed to increase the risk ability of the hierarchical multivariate model. Two-year survival was higher in women: 85 vs 66%; χ(2)=15.7, p<0.0001. Peculiarly, outcome results were similar when only CVD was considered. Females showed a multivariate adjusted hazard ratio (HR) of 0.46. Since a 1-mL/kg/min increment in peak VO2 was equated with a 12% improvement in prognosis, the same gender adjusted HR was achieved when mean peak VO2 was reduced by 5 units in women: thus, a HF woman with peak VO2 of 9 mL/kg/min has the same 2-year outcome as a HF man with peak VO2 of 14 mL/kg/min.

Conclusions: Although HF women have a comparatively lower peak VO2 than men, they live longer. We discovered that the traditional cut point value for peak VO2, i.e. ≤ 14 mL/kg/min is not a "gender-neutral" reference since lumping HF men and women together with the same VO2 value is unlikely to describe the true risk. These preliminary findings do underline the need to assimilate gender-specific issues into clinical practice in HF, when appropriate.