Abstract Funding Acknowledgements Type of funding sources: None. Introduction The electrocardiogram (ECG) is helpful in patients (P) with pulmonary embolism (PE), but it is not present in the existing risk prediction tools, such as the Pulmonary Embolism Severity Index (PESI). Intermediate risk PE encompasses a heterogeneous group of P, with different prognoses, some of whom will need fibrinolytic treatment. This study aims to determine the prognostic impact of ECG in intermediate-risk PE. Methods All P admitted for intermediate-risk PE in an Intensive Cardiac Care Unit between 2007 and 2016 were included. P were followed up for two years for all-cause mortality. Clinical and analytical variables, ECG, echocardiographic, and computed tomography (CT), were collected. Statistical analysis used chi-square and Mann-Whitney U tests, binary logistic regressions, Kaplan-Meier curves, and Cox regression. Results This study included 209 P: mean age 63±18years; 38.5% male. T-wave inversion in leads V1-V3 was present in 81 (38.8%), S1Q3T3 pattern in 51 (24.4%), incomplete right bundle branch block (RBBB) in 27 (12.9%), and complete RBBB in 22 (10.5%). T-wave inversion in leads V1-V3 was associated with syncope at presentation (p=0.032); presence of echocardiographic right ventricle dilation (p=0.003) and abnormal interventricular septal (IVS) motion (p=0.001). S1Q3T3 pattern was associated with syncope (p=0.028); higher heart rate at admission (p=0.001); higher troponin (p=0.013) and BNP (p=0.010) levels; abnormal IVS motion (p=0.004); and increased CT-derived right-to-left ventricle diameter (RV/LV) ratio (p=0.014). RBBB were associated with syncope (p=0.020); higher troponin and BNP levels (p=0.001); and increased RV/LV ratio (p=0.029). For each increase in the number of these ECG findings, there was an increase in the odds of fibrinolytic treatment (OR 1.573, 95%CI 1.150-2.151, p=0.005), and the number of ECG findings was a predictor of fibrinolysis independently from PESI (OR 1.535, p=0.008). In survival analysis, T-wave inversion in leads V1-V3 was associated with decreased survival during follow-up (x2=4.398; p=0.036), even after adjustment for PESI (OR 0.322, p=0.041). Conclusions ECG findings of PE were associated with clinical, analytical and imagiological risk features. They were also predictors of fibrinolysis, and T-wave inversion in leads V1-V3 was associated with decreased survival after adjustment for PESI. Therefore, in the future, incorporation of ECG findings in risk scores might allow better risk assessment in intermediate-risk PE.