Abstract / Summary
Background: Baseline intracavitary haemodynamic measurements frequently demonstrate an inconsistent relationship with exertional performance. This may reflect an incomplete interpretation of left ventricular (LV) filling pressures. LV transmural pressure difference (ΔPTM = LV end-diastolic pressure [LVEDP]-right atrial pressure [RAP]) integrates LV filling pressure with right ventricular/pericardial constraint and may provide a composite representation of resting haemodynamic conditions. Ventilatory efficiency, assessed by the minute ventilation-carbon dioxide production (VE/VCO2) slope during cardiopulmonary exercise testing (CPET), is a leading representation of cardiopulmonary reserves and a powerful prognostic marker in heart failure (HF). Whether ΔPTM is associated with exercise ventilatory efficiency beyond conventional resting filling pressure measurements remains unclear.
Methods: We retrospectively studied 422 patients with advanced HF (LVEF ≤25%) who underwent right-heart catheterization and CPET. ΔPTM was analysed both continuously and by tertiles. The primary outcome was VE/VCO2 slope; peak VO2 was a secondary outcome. Bayesian multivariable regression models were adjusted using a directed acyclic graph-derived confounder set. Sensitivity analyses compared ΔPTM with LVEDP and RAP modelled individually and jointly.
Results: Among 422 patients (mean age 51.3 ± 10.8 years; 62 [14.7%] female), higher ΔPTM was independently associated with a lower VE/VCO2 slope (posterior mean β = -0.34 per mmHg; 95% credible interval [CrI] -0.58 to -0.11; 99.7% posterior probability of a negative association). Unadjusted VE/VCO2 slope decreased from 40.2 (31.7-67.1) in the lowest ΔPTM tertile to 34.9 (30.6-44.8) in the highest tertile (P = .029). The adjusted posterior predictive difference between the highest and lowest ΔPTM tertiles was -4.42 units (95% CrI -7.85 to -0.62). Following multivariable adjustment, ΔPTM showed no significant association with peak VO2 (posterior mean β = +0.06; 95% CrI -0.02 to +0.14). Neither LVEDP nor RAP, modelled individually or jointly, demonstrated independent associations with ventilatory efficiency.
Conclusion: Resting ΔPTM was inversely associated with the VE/VCO2 slope during exercise, whereas no independent association was observed with peak VO2. Compared with individual left- or right-sided filling pressures, ΔPTM provides a parsimonious summary of the balance between left-sided distending pressure and right-sided constraint associated with ventilatory efficiency in advanced HF.