Predictive factors of low cardiac output in patients hospitalized for intermediate-high-risk pulmonary embolism

Abstract

Introduction

The prognosis of patients hospitalized for intermediate-high-risk pulmonary embolism (PE) varies, with an estimated mortality from 3 to 15%. New therapeutic strategies, such as half-dose fibrinolysis or percutaneous reperfusion techniques, are currently under evaluation in this patient group. The role of these therapeutic strategies remains to be defined.

Objective

To identify clinical and paraclinical factors associated with low cardiac output in patients hospitalized for intermediate-high-risk PE.

Method

This prospective observational study included patients hospitalized in cardiac intensive care unit for intermediate-high-risk PE at Lille University Hospital between April 2022 and April 2024. After measuring cardiac index (CI) by right heart catheterization, demographic, clinical, biological, and imaging data were described and compared between patients with CI ≤ 2.5 L/min/m² and those with CI > 2.5 L/min/m². Multivariate logistic regression analysis was performed to identify independent factors associated with low cardiac output.

Results

Among the 82 patients included, 53.7% had a CI ≤ 2.5 L/min/m². This group had biological signs of poor tolerance, including lower prothrombin time (77 vs. 84%, P = 0.014), lower glomerular filtration rate (71 vs. 88 L/min/m², P = 0.003), and lower mixed venous oxygen saturation (57.4 vs. 68.6%, P < 0.001). Patients with low cardiac output had more dilated right ventricles (RV diameter: 36 vs. 33 mm, P = 0.005), reduced RV contractility (TAPSE: 15 vs. 19 mm, P < 0.001; S’tdi wave: 8 vs. 11 cm/s, P < 0.001), higher estimated right atrial pressure on echocardiography (P < 0.001), and higher NT-proBNP levels (4366 vs. 2036 μg/mL, P = 0.001). The two independent predictive factors for low cardiac output were the S’tdi wave measurement and the echocardiographic estimation of right atrial pressure. Clinical parameters did not differ between the two groups. Non-invasive cardiac output measurement via transthoracic echocardiography (TTE) showed good correlation with invasive measurements and acceptable accuracy (mean error of ± 0.40 L/min/m²).

Conclusion

Half of the patients admitted for intermediate-high-risk PE have impaired cardiac output. Identifying these patients based only on clinical parameters is challenging. TTE appears to be the most effective tool for identifying the most severe cases, enabling the consideration of interventional or pharmacological reperfusion therapies.