Right Ventricular Strain and Outflow Tract Velocity Time Integral Are Associated with Mortality in Critically Ill Patients with Pulmonary Embolism

Introduction: High-risk pulmonary thromboembolism (PE) is often fatal due to right ventricular heart failure. However, right ventricular echocardiographic parameters that are associated with adverse outcome in PE are incompletely characterized. Our objective was to evaluate if right ventricular global longitudinal strain (RVGLS) and right ventricular outflow tract velocity-time integral (RVOT VTI) might be indicators of mortality in PE. Methodology: This is an observational study with prospective inclusion from June 1999 to December 2023. Only patients with PE requiring intensive care medicine (ICU) admission were included. The study assessed mortality in the ICU and at 6 months of follow-up, as well as the development of heart failure. The independent variables included clinical and echocardiographic characteristics. Results: A total of 463 PE patients with a mean age of 62.3 ± 21.6 years were included in this study. The ICU and 6-month mortality were 18.4% and 20.7%, respectively. 386 patients were treated with thrombolysis. Multivariable analysis showed that the variables associated with ICU mortality were Pulmonary embolism severity index (PESI) (OR 1.241, 95% CI [1.037-1.587], p<0.001), RVGLS (OR 0.421, 95% CI [0.202-0.774], p<0.001), left atrial reservoir (εs) (OR 0.357, 95% CI [0.141-0.756], p<0.001), right atrial pump (εa) (OR 0.632, 95% CI [0.282-0.887]), the RVOT VTI (OR 0.678, 95% CI [0.321-0.881], p<0.001), and left ventricular outflow tract (LVOT) VTI (OR 0.782, 95% CI [0.413-0.912], p<0.001). Multivariable analysis found that the development of heart failure assessed at 6 months was associated with RVGLS (OR 0.538, 95% CI [0.182-0.785], p=0.001), left atrial strain (εa) (OR 0.313, 95% CI [0.21-0.721], p<0.001), right ventricular basal diameter (OR 1.173, 95% CI [1.018 – 1.892], p<0.001), pulmonary flow acceleration time in RVOT (OR 0.693, 95% CI [0.328 – 0.839], p<0.001), estimated pulmonary artery wedge pressure (PAWP) (OR 1.437, 95% CI [1.131– 2.274], p<0.001), and intracavitary thrombus (OR 1.223, 95% CI [1.117 – 1.973], p<0.001). The variables that were associated with 6-month mortality in the multivariable analysis were PESI (OR 1.029, 95% CI [1.012 – 1.377], p<0.001), RVGLS (OR 0.657, 95% CI [0.438-0.871], p<0.001), RVOT VTI (OR 0.324, 95% CI [0.102-0.541], p<0.001), right atrial pump (εa) (OR 0.352, 95% CI [0.193-0.721], p<0.001), and LVOT VTI (OR 0.814, 95% CI [0.281-0.948], p<0.001), all p-values <0.001. Conclusions: Among patients with PE in the ICU, right ventricular strain and RVOT VTI were associated with mortality in the ICU and at 6-month. Furthermore, right ventricular strain was independently associated with future heart failure. These data emphasize the clinical relevance of right ventricular parameters in prognosticating high-risk PE