Ultrasound-assisted catheter-directed thrombolysis vs. low-dose intravenous tissue-type plasminogen activator treatments in acute intermediate-high risk PE: insights from a retrospective study

Background Ultrasound-assisted catheter-directed thrombolysis (USAT) and intravenous (IV) low-dose tissue-type plasminogen activator (t-PA) therapies have been developed to achieve effective reperfusion with a reduced risk of bleeding in patients with acute pulmonary embolism (PE) at intermediate-high risk (IHR). However, comparisons between these strategies have remained inconclusive. Aims In this single-center acute PE study, we retrospectively evaluated the predictors of efficacy and safety outcomes in patients at IHR treated with USAT versus IV low-dose t-PA. Methods We analyzed 329 patients (USAT n=205; IV t-PA n=124). Changes in clot burden, right ventricular (RV) strain, and RV-PA coupling were assessed. To minimize selection bias and confounding, inverse probability weighting (IPW) based on propensity scores was utilized to balance baseline covariates (including age, PESI score, and comorbidities), followed by weighted multivariable linear and Cox regression analyses to evaluate efficacy and long-term mortality (median follow-up 95.8 months). Results The median follow-up time was 95.8 months (IQR: 76.6–104.3 months). The USAT was performed bilaterally in 82.9 % of procedures, and mean t-PA dose was 38.5 ± 13.6 mg and 27.4 ± 14.5 mg for bilateral and unilateral procedures, respectively. Infusion duration of 25.2 ± 6.6 hours. Significant reductions were observed in PA pressures following USAT. In the low-dose t-PA cohort, the median dose was 50 mg (IQR: 25–50 mg), and second, third and fourth infusions were required in 58.9 %,19.3 % and 11.3 % of patients, respectively. The reductions in heart rate and in RV/LV ratio were more pronounced with IV t-PA whereas the lysis of clot was higher with USAT (p<0.001). However, improvements in the oxygen saturation %, tricuspid annular planar systolic excursion and PA systolic pressures (PASP) were comparable between two treatment cohorts. After adjustment for confounders, superiority of USAT over low-dose t-PA in terms of thrombolysis was significant (p< 0.001) while PE recurrence, and in-hospital or long-term mortality rates were not different (p>0.05). A higher PE severity index score independently associated with in-hospital death or PE recurrence (P = 0.003) while an older age (p=0.004), male sex (p=0.012) and a higher PASP (p=0.017) at discharge were predictors for shortened long-term survival. Conclusion In acute PE patients at IHR status, IV low-dose t-PA therapy related to more pronounced improvements in heart rate and RV function while thrombolysis was better with USAT. However, early and late clinical outcomes were comparable between two reperfusion cohorts.