Catheter-Directed Thrombolysis Versus Anticoagulation Monotherapy in Intermediate-High Risk PE

Treatment of intermediate risk PE is still debated. Despite the promising results of small studies on the efficacy and safety of systemic thrombolytic therapy, larger trials failed to show a net clinical benefit. Pulmonary EmbolIsmTHrOmbolysis (PEITHO) trial which compared the full-dose systemic thrombolysis (i.e., tenecteplase) versus anticoagulation therapy in patients with intermediate-risk PE showed significant lower incidence of mortality or hemodynamic collapse in the first 7 days after randomization in patients who received tenecteplase (2.6% vs 5.6% in placebo group, [odds ratio, 0.44; 95% confidence interval, 0.23 to 0.87; P value, 0.02]). However the mortality benefit was neutralized by the increased risk of major bleeding in thrombolytic arm (11.5% vs 2.4% in the tenecteplase and placebo group, respectively. Importantly, during the long-term follow up (median of 37.8 months) of PEITHO participants, the thrombolytic therapy failed to improve the RV right ventricular function, residual dyspnea ( 36% in thrombolysis group vs 30.1% in the placebo group), or mortality rates (20.3% in thrombolysis group vs 18 % in the placebo group ). CTEPH occurred in ( 2.1% in thrombolysis group vs 3.2% in the placebo group. The lack of benefit of full-dose thrombolytic in PEITHO, might have several explanations. Intermediate risk PE compose of heterogenous group of patients with different prognosis in whom one fits all approach would not be applicable. This heterogeneity in prognosis were underlined in the latest guideline of the European Society of Cardiology (ESC) which classified the intermediate-risk PE category into two groups of intermediate-low and intermediate-high risk patients according to the right ventricle function and cardiac biomarker levels. Second, lower-dose thrombolytic regimen might result in the same benefit with lower bleeding events. CDT, by delivering drug locally, claims to increase the efficacy of thrombolytic agents and consequently decrease the required dose which might translate to lower bleeding events.

In an open-label parallel groups blinded-endpoint randomized clinical trial, we aim to evaluate the safety and efficacy of standard catheter-directed thrombolysis (CDT) vs anticoagulation-only therapy in patients with acute intermediate-high risk pulmonary embolism. The hypothesis is that CDT will have a superior efficacy and safety regarding the proportion of patients with a RV/LV ratio > 0.9 at a 3-month follow-up assessed by an imaging core laboratory with the lower complications of major bleeding, severe thrombocytopenia, and vascular access complication.