Abstract Body (Do not enter title and authors here): Introduction:
Catheter-directed thrombolysis (CDT) in patients presenting with pulmonary embolism (PE) is suggested to improve in-hospital outcomes. We aimed to compare the effect of early versus late initiation of CDT on in-hospital outcomes.

Methods:
A systematic review and meta-analysis were conducted according to PRISMA guidelines. A comprehensive search of PubMed, Scopus, Web of Science, and Embase databases was performed from inception to May 2025. Data extraction was conducted independently by multiple reviewers. Statistical analysis was performed using R software version 4.3.2, and odds ratios (ORs) and mean difference (MD) with 95% confidence intervals (CIs) were combined using a random-effects model.
Results:
A total of 6 studies, including 53,472 patients, were included. Early intervention before 24 hours significantly reduced the mortality by 39% in patients with acute PE (OR 0.61, 95% CI [0.44–0.84]; I² = 0%). Moreover, Early intervention before 24 hours significantly reduced the all-cause readmission in patients with acute PE (OR = 0.81 (95% CI: [0.73, 0.89]; I² = 0%). There was no significant difference in risk of major bleeding in early vs late intervention (OR = 0.82 (95% CI: [0.48, 1.39]; I² = 69.3%). In addition, Early intervention before 24 hours significantly reduced the length of hospital stay (LOS) (MD = -3.11 days (95% CI: [-4.33, -1.89]; I² = 0%).

Conclusion:
Early intervention in acute PE showed better clinical outcomes compared to late intervention, with the need for more studies to draw a firm conclusion.