Gong J, Castro RRT, Caron JP, et al. - Across the spectrum of heart failure (HF) defined by left ventricular ejection fraction (LVEF), an incremental risk of 2 year all-cause mortality and HF hospitalization was observed in relation to higher VE/VCO ₂ slope (the ratio of minute ventilation to carbon dioxide production; a measure of ventilatory efficiency). More refined risk stratification may be achieved with a multilevel categorical approach to the interpretation of VE/VCO ₂ slope vs the current binary approach used in clinical practice.

• This is a single-centre retrospective observational study of 1347 patients with HF categorized as HF with reduced (HFrEF, LVEF < 40%, n = 598), mid-range (HFmrEF, 40% ≤ LVEF < 50%, n = 164), and preserved (HFpEF, LVEF ≥ 50%, n = 585) LVEF.

• Four ventilatory efficiency categories (VC) were described: VC-I, VE/VCO ₂ slope ≤ 29; VC-II, 29 < VE/VCO ₂ slope < 36; VC-III, 36 ≤ VE/VCO ₂ slope < 45; and VC-IV, VE/VCO ₂ slope ≥ 45.

• Composite outcome (all-cause mortality or HF hospitalization) occurred in 201 patients during a median follow-up of 2.0 (interquartile range: 1.9, 2.0) years.

• Three-fold, five-fold, and eight-fold elevated risk for the composite outcome was noted in patients in VC-II, III, and IV, vs those in VC-I.

• This incremental risk was seen across HFrEF, HFmrEF, and HFpEF cohorts.