Pulmonary artery thrombectomy a safe alternative to thrombolytics

Thrombectomy using the Inari FlowTriever Catheter (FT) is safe and effective as a frontline therapy for acute massive and intermediate-to-high risk pulmonary embolism (PE) even with contraindications to thrombolysis [1].

Treatment of large or intermediate-to-high risk PE is usually with thrombolytic agents; however, 30-40% of patients suffering from PE have contraindications to thrombolytic therapy. The Inari FlowTriever Catheter (IT) was developed to perform pulmonary artery thrombectomy, thus providing an alternative to thrombolytic management.

In a recent retrospective, single-centre, single-group study of 139 patients (70 men and 69 women), pre-procedural imaging stratifying the patients into either high-risk PE in 16 (11.5%) of the patients, or an intermediate-to-high risk PE in 123 (88.5%) of the patients. Thrombolytic therapy was contraindicated in 60 (43%) of them. The primary endpoints of this study were right ventricular/left ventricular (RV/LV) ratios were determined and compared before and after FT, and in-hospital mortality.

Of the 139 patients, 131 had completed computed tomography angiograms (CTA) and 6 had completed transthoracic echocardiograms (TTE), for a total of 137/139 (98.6%) who had imaging completed prior to undergoing thrombectomy. Following thrombectomy, 9 patients underwent CTA, and 119 TTE, for a total of 128/139 (92.1%). Using these images, RV/LV ratios were determined and compared before and after FT.

The primary endpoint was met. Comparing pre-thrombectomy RV/LV ratios to post-thrombectomy RV/LV ratios, the mean pre-FT RV/LV ratio was 1.49 and post-FT it was 0.81 (HR 0.69; 95% CI 0.63-0.75, or 44% reduction [95% CI 41-47%]) in the intermediate-high risk PE cohort and about the same in the high-risk PE cohort (HR 0.71; 95% CI 0.47-0.95, or 42% reduction [95% CI 32-52%]).

The  pre- and post- FT pulmonary arterial pressure data supported a benefit across both risk groups: a mean reduction of 8.9 mmHg (95% CI 7.7-10.2)  corresponding to a 28% drop (95% CI 24-32%) was measured in the intermediate-high risk cohort, and an even larger drop of 13.4 mmHg (95% CI 9.2-17.5) was observed in the high-risk PE cohort, corresponding to a 36% drop (95%CI 25-47%).

Among the 139 patients, only 3 (2.1%) lost >5 g/dL haemoglobin; 2 of these required extracorporeal membrane oxygenation for massive PE.

Among all patients, there were 6 mortality events (4.3%), 5 of whom belonged to the high-risk PE cohort (total 16 patients, so 31.3% mortality), and 1 of whom belonged to the intermediate-to-high risk PE cohort (mortality 0.8%).

In conclusion, in this series of 139 patients, FT appears to be safe and effective for resolving acute massive and intermediate-high risk PE, even as first-line therapy. Furthermore, FT provides non-thrombolytic option to the 40% of patients with contraindication to thrombolytic medications.

 

1. 
   
   1. Cottrell, J. Real World Outcomes of Flowtriever pulmonary artery thrombectomy at a tertiary care hospital. Abstract 905-04, ACC 2021 Scientific Session, 15-17 May.

 



Posted on 19 May 20216 July 2021