The Prognostic Value of Right Ventricular End‐Diastolic Basal Diameter Index by Echocardiography in Connective Tissue Diseases Associated With Pulmonary Artery Hypertension

ABSTRACT Background Right ventricular (RV) failure is a well‐recognized pivotal prognostic factor of adverse outcomes in pulmonary artery hypertension (PAH), while RV dilation provides significant implications for adaptive or maladaptive changes. PAH is a predominant cause of mortality among patients with connective tissue disease (CTD). This study aims to elucidate the prognostic significance of RV morphology, as assessed by echocardiography (ECHO), in with CTD associated with PAH (CTD‐PAH). Methods In this ambispective cohort study, 143 CTD‐PAH patients diagnosed by right‐sided heart catheterization (RHC) from 2013 to 2023 were enrolled. Clinical characteristics, laboratory data, echocardiographic parameters (right ventricular end‐diastolic basal diameter index (RVDDI), tricuspid annular plane systolic excursion (TAPSE) and pulmonary arterial systolic pressure (PASP)) and therapy were recorded. The primary endpoint was defined as clinical worsening within a five‐year timeframe. Analytical methods included Kaplan–Meier survival analyses, the log‐rank test, and multivariable Cox proportional hazards regression to evaluate prognostic factors. Results The study enrolled a total of 143 patients with CTD‐PAH, with a notable female predominance (95.1%) and a median age of 41.67 years; SLE‐PAH (49%) and pSS‐PAH (34%) were the most common subtypes, and 94% of the participants were in WHO‐FC II‐III. Among the participants, 34 (23.8%) patients experienced clinical worsening during a median follow‐up period of 21 months. After adjusting for confounders such as age and sex, RVDDI, as determined by ECHO was correlated with clinical worsening (HR 1.090; 95% CI: 1.019–1.166; p  = 0.012). RVDDI > 25.81 mm/m 2 predicts higher incidence of clinical worsening in CTD‐PAH. In the subgroup of TAPSE/PASP > 0.19 mm/mmHg, patients with RVDDI > 25.81 mm/m 2 had a higher incidence of clinical worsening. The estimated event‐free survival rates at 1 and 3 years were 93.5% and 53.7%, respectively. Conclusion The study demonstrates that RVDDI, as evaluated by ECHO, is a significant prognostic indicator for clinical worsening in CTD‐PAH. Its inclusion in the assessment of RV function and risk stratification may provide valuable incremental prognostic information for this CTD‐PAH population.