Which Diastolic Pressure Should Be Used to Assess Diastolic Function?

Abstract

Background: Although high left ventricular filling pressures [left ventricular (LV) end-diastolic pressure or pulmonary capillary wedge pressure (PCWP)] are widely taken as surrogates for LV diastolic dysfunction, the actual distending pressure that governs LV diastolic stretch is transmural pressure difference (∆PTM). Clinically, preferring ∆PTM over PCWP may improve diagnostic and therapeutic decision-making. We aimed to compare the clinical implications of diastolic function characterization based on PCWP or ∆PTM.

Methods: We retrospectively screened our hospital database for adult patients with a clinical diagnosis of heart failure who underwent right heart catheterization. Echocardiographic diastolic dysfunction was graded according to the current guidelines. LV end-diastolic properties were assessed with construction of complete end-diastolic pressure-volume relationship (EDPVR) curves using the single-beat method. Survival status was checked via the electronic national health-care system.

Results: A total of 693 cases were identified in our database; the final study population comprised 621 cases. ∆PTM-based, but not PCWP-based, EDPVR diastolic stiffness constants were significantly predictive of advanced diastolic dysfunction. PCWP-based diastolic stiffness constants were not able to predict 5-year mortality, whereas ∆PTM-based EDPVR stiffness constants and volumes all turned out to have significant predictive power for 5-year mortality.

Conclusion: Left ventricular diastolic function assessment can be improved using ∆PTM instead of PCWP. As ∆PTM ultimately linked to right-sided functions, this approach emphasizes the limitations of taking LV diastolic function as an isolated phenomenon and underlines the need for a complete hemodynamic assessment involving the right heart in therapeutic and prognostic decision-making processes.

Figure 1.

Left ventricular (LV) end-diastolic pressure–volume relationship (EDPVR) characterizes LV diastolic properties. The curve can be defined as LVEDP = α(LVEDV)^β, where LVEDP is left ventricular end-diastolic pressure, LVEDV is left ventricular end-diastolic volume, α and β are constants that define the steepness of EDPVR curve. V₀ and V₃₀ are LV volumes at 0 and 30 mm Hg, respectively. Mechanistically, V₀ represents remodeling; higher values indicate a more dilated LV. V₃₀ represents a measure of ventricular stiffness; higher values indicate a more compliant LV. ∆P_TM-based, but not PCWP-based, EDPVR diastolic stiffness constants were significantly predictive of grade II or III diastolic dysfunction. PCWP-based diastolic stiffness constants were not able to predict 5-year mortality, whereas ∆P_TM-based EDPVR stiffness constants and volumes all turned out to have significant predictive power for 5-year mortality. ∆P_TM, transmural pressure difference; EDPVR_sb, single-beat end-diastolic pressure–volume relationship; LVEDP, left ventricular end-diastolic pressure; LVEDV, left ventricular end-diastolic volume; PCWP, pulmonary capillary wedge pressure; P_PCW, pulmonary capillary wedge pressure; P_RA, right atrial pressure; SV, stroke volume.

Figure 2.

Median left ventricular (LV) end-diastolic pressure–volume relationship (EDPVR) curves with shaded areas representing interquartile ranges. The pulmonary capillary wedge pressure (PCWP)-based approach systematically estimates a stiffer LV compared to an LV transmural pressure difference (∆P_TM) one. ∆P_TM, transmural pressure difference; EDPVR_sb, single-beat end-diastolic pressure-volume relationship; LVEDP, left ventricular end-diastolic pressure; LVEDV, left ventricular end-diastolic volume; PCWP, pulmonary capillary wedge pressure. *∆P_TM significantly superior compared to PCWP in predicting echocardiographic grade II or III diastolic dysfunction. ^†∆P_TM significantly superior compared to PCWP in predicting 5-year mortality.