Noninvasive assessment of pulmonary vascular resistance: a synergistic approach using computed tomography pulmonary angiography and echocardiography in pulmonary hypertension

Abstract

Background: Pulmonary vascular resistance (PVR) is essential in managing pulmonary hypertension (PH) and has prompted the search for noninvasive assessment techniques. This study investigates the integration of morphological parameters from computed tomography pulmonary angiography (CTPA) and functional parameters from transthoracic echocardiography (TTE) to develop a noninvasive method for evaluating PVR in patients with PH.

Methods: Data from PH patients who underwent CTPA, TTE, and right heart catheterization (RHC) were analyzed retrospectively. The Cobb angle, defined as the angle between the spine and interventricular septum, was calculated by CTPA. It is assumed that thorax geometry, pericardial morphology, and body surface area (BSA) are factors influencing the Cobb angle measurement, and these factors were adjusted for in the analysis. Multiple linear regression was performed to evaluate the multivariate ability to predict PVR. Multivariate Cox regression analysis assessed the prognostic value of parameters in predicting hospitalization for heart failure.

Results: In total, 78 patients meeting the criteria were enrolled. Among the TTE parameters, the right ventricular outflow tract acceleration time (RVOT-AT) demonstrated the best goodness-of-fit to PVR (R²=0.433, P<0.001). Correcting the Cobb angle by BSA significantly improved its fit to PVR (R²=0.510, P<0.001), compared to the uncorrected angle (R²=0.450, P<0.001). The model combining Cobb angle/BSA and RVOT-AT strongly predicted PVR (r=0.815, R²=0.634, P<0.001) and was effective across different demographics. After multivariable adjustment, the Cobb angle [hazard ratio (HR): 1.057; P<0.001], Cobb angle/BSA (HR: 1.087; P<0.001), tricuspid annular plane systolic excursion (TAPSE) (HR: 0.878; P=0.014), RVOT-AT (HR: 0.968; P=0.030), and right ventricular myocardial performance index (RVMPI) (HR: 5.324; P<0.001) remained significant independent predictors of heart failure.

Conclusions: The integration of BSA-adjusted morphological markers from CTPA with hemodynamic parameters derived from TTE provides a promising noninvasive method for predicting PVR and demonstrates significant prognostic value in evaluating heart failure in PH patients.

Keywords: Cardiovascular; computed tomography pulmonary angiography (CTPA); pulmonary hypertension (PH); pulmonary vascular resistance (PVR); transthoracic echocardiography (TTE).

Figure 1

Measurements were selected at the level with the largest biventricular area in diastole. (A) Showed the Cobb angle was 70.4°; (B) demonstrated the measurement of the thoracic longitudinal diameter (a) and the thoracic transverse diameter (b); (C) showed the measurement of the pericardial longitudinal diameter (c) and the pericardial transverse diameter (d).

Figure 2

Scatter plot of the relationship between RVOT-AT, LnRVOT-AT and PVR. PVR, pulmonary vascular resistance; RVOT-AT, right ventricular outflow tract acceleration time; WU, Wood Unit.

Figure 3

Cobb angle, Cobb angle/BSA combined with RVOT-AT to evaluate PVR respectively. BSA, body surface area; PVR, pulmonary vascular resistance; RVOT-AT, right ventricular outflow tract acceleration time; WU, Wood Unit.

Figure 4

Bland-Altman analysis shows the consistency of PVR obtained from RHC with predicted values. BSA, body surface area; PVR, pulmonary vascular resistance; RHC, right heart catheterization; RVOT-AT, right ventricular outflow tract acceleration time; WU, Wood Unit.

Figure 5

Kaplan-Meier curves of TTE and CTPA parameters. BSA, body surface area; CTPA, computed tomography pulmonary angiography; RVMPI, right ventricular myocardial performance index; RVOT-AT, right ventricular outflow tract acceleration time; S’, tricuspid annular systolic peak velocity; TAPSE, tricuspid annular plane systolic excursion; TTE, transthoracic echocardiography.