Is pulmonary vascular remodeling an intermediate link between hyperglycemia and adverse outcomes in patients with idiopathic pulmonary arterial hypertension? Insights from a multi-center cohort study

Background Hyperglycemia upon admission is associated with poor prognosis of many cardiovascular diseases. However, the relationship of stress hyperglycemia ratio (SHR), admission blood glucose (ABG), and hemoglobin A1c (HbA1c) with pulmonary hypertension has not been reported. This study aimed to explore the association of hyperglycemia indices with disease severity and long-term adverse outcomes in patients with idiopathic pulmonary arterial hypertension (IPAH). Methods This multi-center cohort study included 625 consecutive patients diagnosed with or treated for IPAH between January 2015 and June 2023. SHR was calculated using the followings: ABG (mmol/L)/(1.59 x HbA1c [%] - 2.59). The primary endpoint was defined as clinical worsening events. Multivariable Cox regression and restricted cubic spline analyses were employed to evaluate the association of SHR, ABG, and HbA1c with endpoint events. The mediating effect of pulmonary hemodynamics was evaluated to investigate the potential mechanism between hyperglycemia and clinical outcomes. Results During a mean follow-up period of 3.8 years, 219 (35.0%) patients experienced all-cause death or clinical worsening events. Hyperglycemia indices correlated with well-validated variables that reflected the severity of IPAH, such as the World Health Organization functional class, 6-min walk distance, and N-terminal pro-brain natriuretic peptide levels. Multivariable Cox regression analyses indicated that SHR (hazard ratio [HR] 1.328, 95% confidence intervals [CI]: 1.185, 1.489 per 0.1-unit increment, P < 0.001) and ABG (HR 1.317, 95% CI: 1.134, 1.529 per 1.0-unit increment, P < 0.001) were independent predictors of primary endpoint events. Mediation analysis indicated that pulmonary vascular resistance mediated 5.65% and 14.62% of the associations between SHR and ABG and clinical worsening events, respectively. The addition of SHR significantly improved reclassification, discrimination ability, and model fit beyond the clinical risk prediction model. Conclusions SHR is positively associated with clinical worsening in patients with IPAH. The association appeared to be partially mediated through the pathway of pulmonary vascular remodeling, indicating that SHR may serve as a valuable indicator for providing additional risk information.