Background: Although high left ventricular filling pressures [left ventricular (LV) enddiastolic 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 (∆P TM ).Clinically, preferring ∆P TM over PCWP may improve diagnostic and therapeutic decision-making.We aimed to compare the clinical implications of diastolic function characterization based on PCWP or ∆P TM . 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.∆P TM -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 ∆P TM -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 ∆P TM instead of PCWP.As ∆P TM 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.