Abstract Body (Do not enter title and authors here): Introduction
Treatment for acute pulmonary embolism (APE) includes both noninvasive and invasive strategies. Transthoracic echocardiography (TTE) is the predominant test to assess right ventricular (RV) function following function, which is associated with adverse clinical outcomes. However, specific methods to measure RV function in clinical practice vary and have not been well-studied in the setting of APE. We sought to determine whether invasive treatment for APE was more effective than noninvasive treatment at achieving normal RV function as determined by various TTE measures.

Methods
Data for 108 individuals treated for APE at our institution were retrospectively reviewed. All post-treatment TTE were performed within 72 hours of admission and prior to hospital discharge. There were no in-hospital mortalities. Logistic regression analysis was used to identify independent predictors of normal RV function defined as TTE-measured right ventricular-to-left ventricular diameter (RV/LV) ratio ≥ 0.9, tricuspid annular plane systolic excursion (TAPSE) ≥ 17.0mm, fractional area change (FAC) ≥ 35.0%, and right ventricular free wall strain (RVFWS) ≤ -20.0%. Independent variables chosen for analysis were: patient age, initial heart rate, syncope on presentation, presence of saddle PE on computed tomography, and having received invasive treatment for APE (catheter-directed thrombolysis, catheter-directed thrombectomy, or surgical thrombectomy).

Results
Mean age was 61.5 (±17.7) years and 50.0% were male. Mean heart rate on presentation was 101 (±18) per minute. 16.7% presented with syncope and 23.1% were diagnosed with saddle. 55 (50.9%) patients were treated invasively, of whom 15 received catheter-directed thrombolysis, 36 mechanical thrombectomy, and 4 surgical thrombectomy. RV function data were as follows: RV/LV ratio = 0.95(±0.22), TAPSE = 18.9(±5.4) mm, FAC = 32.4(±4.4) %, RVFWS = -18.9 (±4.6) %. Invasive treatment was an independent predictor of normal RVFWS (p=0.04, odds ratio 2.6, 95%CI 1.1 - 6.8), but not of other measures of RV function. No other variables independently predicted any of the measures of normal RV function.

Conclusion
An invasive treatment strategy for APE is more effective than a noninvasive strategy in achieving normal RV function as measured by RVFWS. Other measures were not associated with APE treatment type, suggesting that RVFWS should be the method of choice to assess RV function.