Dicrotic notch index in pulmonary hypertension: correlation with hemodynamic, echocardiographic and clinical parameters

Introduction:
Pulmonary hypertension (PH) is characterized by increased pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) due to loss of arterial elasticity and vascular obstruction. The dicrotic notch index (DNI) represents reflected wave characteristics and vascular elasticity, potentially serving as an important marker in PH assessment.

Aim:
This study evaluates the relationship between DNI and PVR, PAPs, and other hemodynamic and clinical parameters in PH patients.

Material and methods:
A retrospective analysis was conducted on 76 patients diagnosed with pulmonary arterial hypertension (PAH), chronic thromboembolic pulmonary hypertension (CTEPH), or normal PAPs who underwent right heart catheterization (RHC). PAP waveforms were analyzed to determine DNI. Correlations between DNI and hemodynamic, clinical, and echocardiographic parameters were assessed using Pearson’s correlation coefficient. Logistic regression and ROC analysis were performed to evaluate the DNI’s predictive value.

Conclusions
DNI showed significant positive correlations with systolic PAP (sPAP) (r = 0.972, p < 0.001), diastolic PAP (dPAP) (r = 0.876, p < 0.001), mean PAP (mPAP) (r = 0.987, p < 0.001), right atrial (RA) pressure (r = 0.741, p = 0.018), and PVR (r = 0.814, p < 0.001). Significant negative correlations were observed with cardiac index (CI) (r = –0.573, p = 0.012) and pSO₂ (r = –0.516, p = 0.043). Univariable logistic regression identified DNI as a significant predictor of PH (OR = 1.100, 95% CI: 1.048–1.155, p < 0.001). ROC analysis showed an AUC of 0.922 for DNI, indicating excellent predictive value.

Conclusions:
DNI is correlated with key hemodynamic parameters such as PVR and mPAP, underscoring its potential as a crucial marker in the assessment of PAH and CTEPH patients. Additionally, DNI exhibited significant correlations with echocardiographic measurements and clinical indicators, suggesting its utility in evaluating pulmonary arterial stiffness and resistance. Further research is needed to validate these findings in larger cohorts and to establish standardized protocols for DNI measurement in clinical practice.