The Use of Transthoracic Echocardiograms in Hospitalized Adult Patients with Acute Pulmonary Embolism

Background: The role of inpatient transthoracic echocardiography (TTE) in patients with acute pulmonary embolism (PE) is unclear. Although right ventricular dysfunction (RVD) predicts adverse outcomes in acute PE, there is no consensus on the optimal TTE findings for prognostication and how they influence management, particularly when CT and/or an elevated cardiac troponin already suggest RVD. Understanding current practices regarding inpatient TTE in acute PE can help direct appropriate use. Our objectives were to (i) characterize inpatient TTE use in adult patients hospitalized with acute PE, (ii) describe and compare findings of RVD by TTE, CT and troponin, and (iii) explore differences in outcomes between patients managed with or without TTE.

Methods: We conducted a retrospective cohort study of adult patients hospitalized with acute PE at two academic hospitals in Hamilton, Canada between January and December 2018. Patients with suspected PE that was not objectively confirmed, or PE diagnosed prior to hospitalization were excluded. We also excluded patients who had a TTE prior to the diagnosis of PE. Chi-square tests and independent t-tests were used. P-values less than 0.05 were considered significant.

Results: We identified 178 adult patients (mean age 66 ± 15 years; 42% male). Patients were admitted to internal medicine (53%), oncology (19%), surgical specialties (13%) and intensive care units (ICU, 11%). Of 146 patients, 134 (92%) had a PE involving segmental or larger vessels. TTE was conducted in 86 (48%) patients. Systemic thrombolysis was administered to 11 (6%) patients.

A higher proportion of patients with an elevated troponin (66% vs. 35% p<0.001) or evidence of RV strain on CT (65% vs. 35%, p=0.001) underwent TTE compared to those without these findings. Patients admitted to the ICU more frequently underwent TTE (69% vs. 44%, p=0.012). RV size and function were normal in 49 (59%) and 53 (63%) cases, respectively.

Patients with RV strain on CT were more likely to have RV enlargement (58% vs. 30%, p=0.04) and RVD (58% vs. 25%, p=0.011) on TTE. However, right ventricular internal dimension in diastole (RVIDd) (3.9 ± 0.75 cm vs. 3.7 ± 0.78 cm) and tricuspid annular plane systolic excursion (TAPSE) (1.8 ± 0.44 cm vs. 2.0 ± 0.38 cm) were not statistically different between patients with or without RV strain on CT. A higher proportion of patients with an elevated troponin had RV enlargement (58% vs. 14%, p=0.001) and RVD (50% vs. 18%, p=0.018) on TTE.

Length of hospital admission (16 ± 28 days vs. 11 ± 23 days) and in-hospital death (7% vs. 11%) were not statistically different between patients with or without TTE.

Conclusions: Inpatient TTE is conducted frequently in hospitalized patients with acute PE, especially in those with evidence of RV strain based on CT and/or an elevated cardiac troponin. Our results suggest that patients with findings of RV strain on CT are more likely to have RV enlargement and RVD on TTE. Future studies should evaluate the diagnostic utility of CT and/or troponin for RVD in the setting of acute PE, which may reduce the routine use of inpatient TTE and associated healthcare resources and costs.