Studied variables
We documented temporal data, demographic characteristics (sex, age, race), clinical presentation (signs and symptoms), setting (Emergency Department (ED), outpatient clinic, inpatients) and, when available in electronic medical records, lag time from clinical onset to diagnosis, previous medical observations and complementary investigation. Patients admitted with PE symptoms were classified as outpatients, as opposed to patients who were primarily hospitalized for other reasons, referred to as inpatients. Imagological exams, including Computed Tomography with Pulmonary Angiography (CTPA), ventilation-perfusion (VQ) scan, chest X-ray (CXR), echocardiogram (ECHO), electrocardiogram (ECG)), venous compressive ultrasound (CUS) with Doppler, and laboratory tests (D-dimer, troponin I or B-type natriuretic peptide levels) at diagnosis were registered. Anatomic distribution of the thrombus was classified as central, lobar, segmental or sub-segmental, according to the most central segment of the pulmonary arterial tree affected.
Risk stratification followed the American Heart Association’s Scientific Statement, (17) using age-appropriate reference values for heart rate and blood pressure. (18) Massive (high risk) PE was defined by the presence of hypotension, bradycardia or poor peripheral perfusion, whereas sub-massive (intermediate risk) PE was defined by right ventricular strain/injury and/or elevated cardiac biomarkers (troponin I or B-type natriuretic peptide) in non-hypotensive patients. Right ventricular strain/injury was defined by dilation and/or systolic dysfunction on ECHO or CTPA or by ECG changes: new complete or incomplete right bundle – branch block, anteroseptal ST alterations or T wave inversion. The remaining cases were considered non-massive PE (low risk).
Associated deep venous thrombosis (DVT), data on thrombophilia testing and the presence of other underlying risk factors were noted. Obesity was considered when the body mass index was above the 95th percentile for age and sex. Therapeutic and support interventions and secondary prophylaxis were investigated. Outcomes included: PE-related mortality and all-causes mortality during hospitalization and follow up, recurrent VTE, chronic PE (persistence of thrombus in the same territory), chronic thromboembolic pulmonary hypertension (CTPH) and post-thrombotic syndrome (PST).
Finally, we applied PE risk stratification clinical scores, including the Wells criteria, the PERC tool and two pediatric criteria15,16, to our population and evaluated their sensitivity.