Left atrial mechanics and ventilatory performance in HFpEF patients evaluated with simultaneous cardiopulmonary exercise test and stress echocardiography

Background In heart failure and preserved ejection fraction (HFpEF), left atrial (LA) dysfunction reflects not only atrial remodeling but also the magnitude of ventricular filling pressures, especially during exercise. Although the minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) is a well-established marker of ventilatory inefficiency and poor prognosis, the direct correlation between atrial mechanics and ventilatory response to exercise is not yet fully defined in HFpEF patients. Purpose To investigate the association between left atrial reservoir function (LASr) during exercise and VE/VCO2 slope, compared to the conventional LA volume indexed (LAVi) and E/e’ ratio at peak exercise, in HFpEF and in controls. Methods 52 HFpEF patients (age: 74,6 ± 8; BMI: 27,6 ± 4,4) and 30 control subjects underwent to a simultaneous cardiopulmonary exercise test and stress echocardiography (CPET-SE) with parallel assessment of lung diffusing capacity at rest (with DLCO calculation), pulmonary congestion (evaluated with lung B-lines) and NT-proBNP both at rest and at peak of maximal symptom-limited effort. LASr was assessed with speckle tracking echocardiography at rest (Rest_LASr) and during exercise (Ex-LASr) along with LAVi and E/e’ ratio. Ventilatory inefficiency was measured at CPET by VE/VCO2 slope. Results HFpEF patients exhibited lower values of LASr, LAVi and E/e’ at rest and during exercise compared to controls (Table 1); Ex_LASr demonstrated a significant negative correlation with VE/VCO2 slope in HFpEF group (Figure 1; R = -0, 53; p < 0,001) and not for controls. No correlations was found between LAVi/E/e’ and VE/VCO2 both in HFpEF and in healthy subjects. Moreover, HFpEF patients had a worse lung diffusing capacity along with more pulmonary congestion exacerbated by exercise and a higher level of NT-proBNP values. Conclusions Exercise left atrial reservoir strain is a key determinant of hemodynamic performance and its impairment during exercise is related to ventilatory inefficiency in HFpEF. Findings reinforce the concept that an impaired atrial mechanics triggers an increased pulmonary engorgement and elevated dead space and maladaptive ventilation.Figure 1Table 1