Background: Pulmonary embolism (PE) represents a major threat to the life and well-being of a large number of patients worldwide. Once a diagnosis of PE is made, patients should receive appropriate treatment without delay. Massive PE is treated with thrombolytic therapy and low-risk PE is treated with anticoagulation. In patients with acute sub-massive pulmonary embolism, although systemic thrombolysis improves right ventricular (RV) dilatation but it is associated with major bleeding, and is withheld in many patients at risk. This single-arm single-center study investigated whether catheter-directed thrombolysis (CDT) improves right ventricular dilatation, function, and pulmonary artery pressure (reverse right ventricular remodeling) without an increase in major bleeding. Methods and Results: Twenty-five patients
with acute sub-massive PE and mean age of 55±04 years were included in this study. Sixty % of the study subjects were male. Eligible patients had right ventricular dysfunction on echocardiography and elevated ProBNP as well as myocardial injury as detected by cardiac biomarkers (positive test for cardiac troponin T). The CDT regimen of 1 mg per lung per hour recombinant tissue plasminogen activator (rapt) over 12 hours (24 mg rtPA for bilateral PE and 12 mg for unilateral PE) via the ultrasound assisted infusion catheter (EKOS) or Pigtail catheter (n=7; EKOS infusion catheter and n=18; Pigtail catheter). Primary outcomes were change in right ventricular end diastolic diameter (RVEDD), right ventricular end-diastolic dimeter/left ventricular end-diastolic dimeter ratio (RVEDD/LVEDD ratio), right ventricular systolic function (RV-TAPSE and TASV) and the systolic pulmonary artery pressure (sPAP) from baseline to 48 hours after CDT. Safety outcomes included all‐cause mortality and the treatment‐associated morbidity (i.e. major and minor bleeding). Outcomes was reported at time points of 48 hours and 90 days after treatment. The average echocardiographic RVEDD were reduced from 4.8 cm to 4 cm which is statistically significant (P < 0.05), RVEDD/LVEDD ratio decreased from 1.1 (range from 0.9 to 1.6) at baseline to 0.9 (range from 0.8 to 1.2) at 48 hours (P < 0.001), the RV-TAPSE was 1.3 cm and increased to 1.8 cm
48 hours after CDT (P value < 0.05) and the RV-TASV was 7.9 cm/s and increased to 10.5 cm/s 48 hours after CDT (P value < 0.001), and sPAP reduced from 50.22 mmHg (Range from 26 to 100 mmHg) before treatment to 33.3 mmHg (Range from 20 to 93 mmHg) (P value < 0.05) 48 hours after treatment. Within 90 days after CDT, only 3 minor bleeding
episodes but no hemodynamic decompensation, recurrent venous thromboembolism, major bleeding complications or death. Conclusion: CDT improves (reverses) right ventricular remodeling in patients with acute sub-massive PE effectively and safely. Future studies will further define the role of CDT in comparison to other revascularization strategies in the
management of PE patients at increased risk.