Risk stratification in heart failure with mild reduced ejection fraction

Abstract

Heart failure with mid-range ejection fraction represents a heterogeneous and relatively young heart failure category accounting for nearly 20-30% of the overall heart failure population. Due to its complex phenotype, a reliable clinical picture of heart failure with mid-range ejection fraction patients as well as a definite risk stratification are still relevant unsolved issues. In such a context, there is growing interest in a comprehensive functional assessment by means of a cardiopulmonary exercise test, yet considered a cornerstone in the clinical management of patients with heart failure and reduced ejection fraction. Indeed, the cardiopulmonary exercise test has also been found to be particularly useful in the heart failure with mid-range ejection fraction category, several cardiopulmonary exercise test-derived parameters being associated with a poor outcome. In particular, a recent contribution by the metabolic exercise combined with cardiac and kidney indexes research group showed an independent association between the peak oxygen uptake and pure cardiovascular mortality in a large cohort of recovered heart failure with mid-range ejection fraction patients. Contextually, the same study supplied an easy approach to identify a high-risk heart failure with mid-range ejection fraction subset by using a combination of peak oxygen uptake and ventilatory efficiency cut-off values, namely 55% of the maximum predicted and 31, respectively. Thus, looking at the above-mentioned promising results and waiting for specific trials, it is reasonable to consider cardiopulmonary exercise test assessment as part of the heart failure with mid-range ejection fraction work-up in order to identify those patients with an unfavourable functional profile who probably deserve a close clinical follow-up and, probably, more aggressive therapeutic strategies.

Keywords: Heart failure; MECKI score; cardiopulmonary exercise test; left ventricular ejection fraction; prognosis.

Figure 1.

Cardiovascular mortality in HFrEF and rec-HFmrEF patients: insights from the metabolic exercise combined with cardiac and kidney indexes (MECKI) score research group. Kaplan–Meier estimator of cardiovascular mortality at 5 years for left ventricular ejection fraction in the overall population (rec-HFmrEF vs. HFrEF) (upper left panel) and for peak oxygen uptake (peak VO₂ ≤55%) (upper right panel), ventilatory efficiency (VE/VCO₂ slope ≥31) (bottom left panel) and both cut-off values (bottom right panel) in the rec-HFmrEF sample. The incidence rate of cardiovascular mortality at 5 years in the overall HFrEF and rec-HFmrEF groups and in the rec-HFmrEF subgroups categorised according to cut-off values of peak VO₂ and VE/VCO₂ slope (central panel). Modified from Magrì et al. rec-HFmrEF: heart failure with recovered mid-range left ventricular ejection fraction; HFrEF, heart failure with reduced left ventricular ejection fraction; peak VO₂: peak oxygen uptake; VE/VCO₂ slope: ventilatory efficiency.

Figure 2.

Cardiovascular risk assessment in HFmrEF according to CPET-derived parameters. HFmrEF: heart failure with mid-range left ventricular ejection fraction; CPET: cardiopulmonary exercise test; peak VO₂: peak oxygen uptake; VE/VCO₂ slope: ventilatory efficiency; VO₂/WR: oxygen uptake/work rate.