Impact of guideline definitions on right ventricular diameter in echocardiography: an automated analysis in controls and patients with pulmonary hypertension.

Abstract

BACKGROUND: To improve standardization, the 2025 American Association of Echocardiography (ASE) guidelines revised the definitions of right ventricular (RV) basal and mid diameters, revising the 2010 ASE and European Society of Cardiology (ESC) definitions. OBJECTIVES: (1) To quantify differences in right ventricular (RV) diameter measurements between the 2010 and 2025 ASE guidelines, (2) to determine its impact on the diagnosis of RV enlargement (RVE), and (3) to compare these findings with a novel automated non-linear centerline-based approach. METHODS: We analyzed 208 healthy volunteers and 221 patients with pulmonary arterial hypertension (PAH). Using custom cardiac contour analysis (C2A) software, RV diameters were measured across three definitions. The 2010 ASE/ESC defines diameters as the maximal dimension in the basal and mid segments. In contrast, the 2025 ASE defines the basal diameter just below the tricuspid valve and the mid diameter at ~ 50% of RV inflow, both parallel to the annulus. The C2A method uses a non-linear RV centerline as a reference to standardize measurement locations: the mid-point is taken at 50% along the centerline, and the basal diameter is defined as the maximum perpendicular distance within the proximal third of the RV. We quantified nominal and relative definition differences and compared sex-specific RVE prevalence in healthy controls. Diagnostic performance (ROC) and outcome prediction (Cox models) are presented. RESULTS: The median age was 63 years in healthy volunteers (52% male) and 48 years in patients with PAH (22% male), with a median pulmonary vascular resistance index (PVRI) of 22 Wood units·m². Compared to ASE/ESC 2010 definitions, ASE 2025 diameters were 15% (basal) and 20% (mid) lower. Using the 2025 definition in healthy controls, basal RVE was observed in 1% of females and 22% of males, while mid-RVE was present in 6% of females and 35.8% of males. The 2010 definition showed slightly better discrimination for PAH (AUC 0.937 vs. 0.898, p < 0.001). However, the prediction of outcomes was similar between the two definitions, with C-statistics of 0.59 (0.53–0.65) and 0.59 (0.53–0.66), respectively. CONCLUSION: Differences in guideline definitions of RV diameters are important to consider when implementing them in clinical practice.