Modified pulmonary artery obstruction index for thrombolysis assessment in intermediate-risk pulmonary thromboembolism

Acute non-high-risk pulmonary thromboembolism (PTE) is generally relieved within months of anticoagulation treatment initiation. However, some patients experience complications. This study aimed to assess the efficacy of urokinase thrombolysis in intermediate-risk PTE using a modified pulmonary artery obstruction index (PAOI). We retrospectively assessed the data of 85 patients with acute PTE and venous thromboembolism of the lower extremities treated between January 2018 and January 2023. All patients underwent inferior vena cava filter implantation and thrombolysis via the dorsal foot vein. We evaluated thrombolysis efficacy using computed tomography pulmonary angiography, Doppler echocardiography, D-dimer (D-D) levels, and PAOI. The effects of age, preoperative D-D level, urokinase dosage, and thrombolysis time on efficacy and safety were analyzed. Complete thrombus dissolution in pulmonary arteries occurred in 67.1% of patients (thrombolysis efficacy, 100%). The modified PAOI/40, artery diameter, and artery-to-aorta diameter ratio showed significant improvements post-thrombolysis. The average daily usage of urokinase ranged from 36.36 × 10 ⁴ to 100 × 10 ⁴ units. Spearman rank correlation test revealed a relationship between PAOI change rate and pre-intervention D-D level ( r  = 0.291; P  = .007) and average daily urokinase dosage ( r = –0.341; P  = .001). In multinomial logistic regression, total urokinase dosage (odds ratio = 1.052, P  = .032) and thrombolysis time (odds ratio = 0.012, P  = .032) were identified as significant factors. During follow-up, thromboembolism recurred in 2 cases; clinical manifestations of right heart insufficiency were not observed in other patients. Higher preoperative D-D levels may suggest a better thrombolytic effect in intermediate-risk acute PTE. An appropriate daily dosage of urokinase may yield good therapeutic effects. Managing urokinase dosage and duration helps prevent serious bleeding complications.