Effectiveness and Safety of Half–dose Thrombolysis in Intermediate–high Risk Pulmonary Embolism: A Retrospective, Single Center Experience

Abstract Background Current guidelines recommend full–dose systemic thrombolysis for acute pulmonary embolism (PE) in high–risk or hemodynamically unstable intermediate–high risk (IHR– PE) patients. Recent trials suggest that a low, half dose (50 mg) of tissue plasminogen activator (HDrtPA) could be a safe, effective alternative with low bleeding risk. We aimed to evaluate whether HDrtPA in IHR–PE could improve right heart function echocardiographic parameters and NT–proBNP levels at discharge, in comparison to unfractionated heparin (UFH) alone. Methods We retrospectively analyzed ninety IHR–PE consecutively admitted to our Intensive Cardiac Care Unit between January 2016 and May 2023. HDrtPA patients (Group A, n=28) received low–dose thrombolytic therapy (0,6 mg/kg, max. 50 mg in 1 hour) plus UFH. Group B included patients were treated with UFH alone. Primary endpoint was an improvement between admission and discharge of tricuspid annular plane systolic excursion (TAPSE), tricuspid velocity (TV), RV– arterial coupling (TAPSE/PASP or pulmonary artery systolic pressure), basal right ventricle diameter (RVD), and NT–proBNP levels. Secondary endpoint involved assessing the occurrence of mortality and bleeding events. Linear regression models were used with Inverse Probability Weighting propensity scores. Due to the low occurrence of death events, this endpoint was investigated only through descriptive statistics. Results Mean age was 73.48 ± 12.49 (mean ± Sd) and n=43 (47.8%) were males (table 1). Group A had improvement of TAPSE/PASP (+0.16, p=0.006, CI 95%: 0.06; 0.27), RVD (–6 mm, p=0.001, CI 95%: –8.61; –3.58), TAPSE (+2.6 mm, p=0.003, CI 95%: 0.77; 4.49) and TV values (–0.46 m/s, p=0.018, CI 95%: –0.8; 0.09), while the decrease in NT–proBNP values (–2048 pg/ml) did not achieve statistical significance (p=0.382, CI 95%: –7101.17; 2413.45). No significant increase in major bleedings was observed between groups (Group A: 3.5%, Group B: 0%) with an acceptable number of minor bleedings (Group A: 25%, Group B: 1.6%). Death occurred in 3 patients in group A (10%) and 1 patient in group B (1.6% – table 2). Conclusions In selected IHR–PE patients, administration of HDrtPA seems to improve right ventricular function, dimensions and RV–arterial coupling in comparison to UFH alone, with an acceptable bleeding and mortality risk. These results should be confirmed in randomized, prospective trials to allow HDrtPA to be fully included in future guidelines.