Pulmonary hypertension (PH) is a frequent condition in patients with heart failure (HF), which complicates the course of the HF syndrome. Irrespective of left ventricular ejection fraction (LVEF), PH is identified in the majority (up to 83%) of patients with HF and is associated with excess mortality. The pathophysiology of PH in HF is driven primarily by backward transmission of elevated LV filling pressure into the pulmonary circulation, thereby causing post-capillary PH defined by a pulmonary arterial wedge pressure (PAWP) > 15 mmHg. However, additional pathogenetic changes in the pulmonary circuit that occur in response to elevated PAWP (i.e. fibroproliferative remodelling of distal pulmonary arterioles) may contribute to a further elevation of pulmonary artery pressure (PAP) and thus more pronounced PH.¹ Elevated PAP and consecutive right ventricular (RV) dysfunction result in end-organ injury to multiple systemic organ systems, including cardio-renal syndrome and liver dysfunction, which are associated with enhanced disease burden and contribute strongly to increased morbidity and mortality.²

The recently updated European Society of Cardiology (ESC)/European Respiratory Society (ERS) Guidelines for the diagnosis and treatment of PH have updated the haemodynamic definitions of PH. Specifically, the threshold to define PH for mean PAP (mPAP) has decreased from ≥25 mmHg to >20 mmHg, and the Guidelines also adapt a pulmonary vascular resistance (PVR) cut-off to define pre-capillary PH (or a pre-capillary component) from previously >3 Wood units (WU) to >2 WU.³ The rationale for the updated haemodynamic criteria was based mainly on recent studies in large cohorts demonstrating that even mild elevations of PAP (in the range of 21–24 mmHg) and PVR (≥2.2 WU) are associated with adverse outcomes,^4,5 and that the upper limit of a normal mPAP (defined by the mean value plus two standard deviations in healthy adults) is ∼20 mmHg.³ In patients with left heart disease including those with HF, post-capillary PH is subcategorized into isolated post-capillary PH (IpcPH) and combined post- and pre-capillary PH (CpcPH), which is now based on a PVR ≤ or >2 WU.

In this issue of the European Heart Journal, Fauvel and colleagues report on the impact of the updated definitions on the prevalence of PH and CpcPH, and on event-free survival in patients with HF.⁶ In a multi-centric study across France, they prospectively enrolled 662 stable patients with left-sided HF and analysed prevalence and survival based on the previous vs. refined 2022 ESC/ERS criteria. Importantly, all patients had undergone right heart catheterization (RHC) for invasive measurement of cardiopulmonary haemodynamics. The authors report two key points.