Large-bore Mechanical Thrombectomy Versus Catheter-directed Thrombolysis in the Management of Intermediate-risk Pulmonary Embolism: Primary Results of the PEERLESS Randomized Controlled Trial

Background: There is a lack of randomized controlled trial (RCT) data comparing outcomes of different catheter-based interventions for intermediate-risk pulmonary embolism (PE). Methods: PEERLESS is a prospective, multicenter, RCT that enrolled 550 intermediate-risk PE patients with right ventricular dilatation and additional clinical risk factors randomized 1:1 to treatment with large-bore mechanical thrombectomy (LBMT) or catheter-directed thrombolysis (CDT). The primary endpoint was a hierarchal win ratio (WR) composite of the following: 1) all-cause mortality, 2) intracranial hemorrhage, 3) major bleeding, 4) clinical deterioration and/or escalation to bailout, and 5) postprocedural intensive care unit (ICU) admission and length of stay, assessed at the sooner of hospital discharge or 7 days post-procedure. Assessments at the 24-hour visit included respiratory rate, mMRC dyspnea score, NYHA classification, right ventricle (RV)/left ventricle (LV) ratio reduction, and RV function. Endpoints through 30 days included total hospital stay, all-cause readmission, and all-cause mortality. Results: The primary endpoint occurred significantly less frequently with LBMT vs CDT (WR 5.01 [95% CI: 3.68-6.97]; P <0.001). There were significantly fewer episodes of clinical deterioration and/or bailout (1.8% vs 5.4%; P =0.04) with LBMT vs CDT and less postprocedural ICU utilization ( P <0.001), including admissions (41.6% vs 98.6%) and stays >24 hours (19.3% vs 64.5%). There was no significant difference in mortality, intracranial hemorrhage, or major bleeding between strategies, nor in a secondary WR endpoint including the first 4 components (WR 1.34 [95% CI: 0.78-2.35]; P =0.30). At the 24-hour visit, respiratory rate was lower for LBMT patients (18.3±3.3 vs 20.1±5.1; P <0.001) and fewer had moderate to severe mMRC dyspnea scores (13.5% vs 26.4%; P <0.001), NYHA classifications (16.3% vs 27.4%; P =0.002), and RV dysfunction (42.1% vs 57.9%; P =0.004). RV/LV ratio reduction was similar (0.32±0.24 vs 0.30±0.26; P =0.55). LBMT patients had shorter total hospital stays (4.5±2.8 vs 5.3±3.9 overnights; P =0.002) and fewer all-cause readmissions (3.2% vs 7.9%; P =0.03), while 30-day mortality was similar (0.4% vs 0.8%; P =0.62). Conclusions: PEERLESS met its primary endpoint in favor of LBMT vs CDT in treatment of intermediate-risk PE. LBMT had lower rates of clinical deterioration and/or bailout and postprocedural ICU utilization compared with CDT, with no difference in mortality or bleeding.