Left ventricular volume and maximal functional capacity in heart failure with preserved ejection fraction: Size matters.

Aims: Emerging evidence suggests that smaller left ventricular volumes may identify subjects with lower cardiorespiratory fitness. Whether left ventricular size predicts functional capacity in patients with heart failure with preserved ejection fraction (HFpEF) is unclear. This study aimed to explore the association between indexed left ventricular end-diastolic volume (iLVEDV) and maximal functional capacity, assessed by peak oxygen consumption (peakVO₂), in stable outpatients with HFpEF.

Methods and results: We prospectively analysed data from 133 consecutive stable outpatients who underwent cardiopulmonary exercise testing and echocardiography on the same day. Data were validated in a cohort of HFpEF patients from San Paolo Hospital, Milan, Italy. A multivariable linear regression assessed the association between iLVEDV and peakVO₂. The mean age was 73.2 ± 10.5 years, and 75 (56.4%) were women. The median iLVEDV, indexed left ventricular end-systolic volume, and left ventricular ejection fraction were 46 ml/m² (30-56), 15 ml/m² (11-19), and 66% (60-74%), respectively. The median peakVO₂ and percentage of predicted peakVO₂ were 11 ml/kg/min (9-13) and 64.1% (53-74.4), respectively. Adjusted linear regression analysis showed that smaller iLVEDV was associated with lower peakVO₂ (p = 0.0001). In the validation cohort, adjusted linear regression analysis showed a consistent pattern: a smaller iLVEDV was associated with a higher likelihood of reduced peakVO₂ (p = 0.004).

Conclusions: In stable outpatients with HFpEF, a smaller iLVEDV was associated with a lower maximal functional capacity. These findings suggest a need for further studies to understand the pathophysiological mechanisms underlying these observations and to explore targeted treatment strategies for this patient subgroup.