Efficacy and Safety of Low‐Dose Prolonged Infusion Thrombolysis With rt‐PA for Acute Intermediate‐High Risk Pulmonary Embolism

ABSTRACT Thrombolytic therapy alleviates pulmonary embolism (PE) symptoms rapidly but increases bleeding risk, with no consistent consensus on acute intermediate‐high risk PE. This study evaluated the efficacy and safety of low‐dose prolonged infusion thrombolysis for acute intermediate‐high risk PE to provide a safer clinical option. A total of 120 patients were collected and divided into anticoagulant (Group A, n = 58) and thrombolytic (Group B, n = 62) groups. Efficacy outcomes included pulmonary artery thrombus clearance rate, 30‐day all‐cause mortality, and 3–6 month pulmonary hypertension incidence; the primary safety outcome was treatment‐related bleeding. Both groups showed improved SBP, DBP, SpO₂, and RV/LV ratio (all p < 0.05) with no inter‐group differences, but Group B had higher thrombus clearance rate ([64.85 ± 17.47]% vs. [41.65 ± 16.19]%, p < 0.001), with similar 30‐day mortality (1.61% vs. 5.17%, p = 0.278). At 1 day, post‐treatment, Group B had higher D‐dimer (26.78 ± 16.57 μg/mL vs. 7.60 ± 7.23 μg/mL) and FDP (91.45 ± 97.37 μg/mL vs. 18.60 ± 26.34 μg/mL, all p < 0.001) but comparable FIB ( p = 0.091); these differences persisted until discharge (all p < 0.05 for D‐dimer/FDP). Although the incidence of bleeding events in group B was numerically higher than that in group A (17.74% vs. 6.90%, p = 0.073), the difference between the two groups was not statistically significant. No fatal bleeding, intracranial hemorrhage, or recurrent pulmonary embolism occurred in either group. Group B had lower 3–6 month pulmonary artery systolic pressure (PASP) (30.70 ± 9.70 vs. 34.44 ± 10.04 mmHg, p = 0.045) and pulmonary hypertension incidence (27.87% vs. 54.55%, p = 0.004). Thrombus clearance rate correlated with treatment group ( r = 0.57, p < 0.001), and D‐dimer ( r = 0.42) and FDP ( r = 0.32) levels at 1 day post‐treatment (both p < 0.001). Low‐dose prolonged infusion can effectively clear pulmonary artery thrombi in patients with acute intermediate‐high‐risk PE, which may be associated with a reduced incidence of pulmonary hypertension. Patients in the thrombolysis group showed significant dynamic changes in D‐dimer and FDP levels, which were significantly correlated with a higher thrombus clearance rate.