Outcomes in Patients Treated with FlowTriever for Pulmonary Embolism

Purpose: The FlowTriever (Inari Medical, Inc, Irvine, CA) thrombectomy device is designed to remove pulmonary embolus (PE). Reduction in mean pulmonary artery pressure (PAP) and right ventricular–to–left ventricular (RV/LV) ratios have previously been described. This study aims to quantify the change in clot burden using the CT Obstruction Index (CTOI; Qanadli Score) and RV function.

Materials and Methods: Seventeen consecutive patients with massive and submassive PE underwent thrombectomy with the device between December 2018 and August 2019. Pre and post computed tomography angiograms (CTAs) were available for review in 15 of 17 patients. Two physicians determined the pre- and postintervention CTOI for each patient. The RV/LV ratios were also obtained from CTAs. If available, pre- and postintervention echocardiograms and intraprocedural PAP were also compared. Ten patients had pre- and postintervention echocardiograms. Thirteen patients had pre- and postprocedural PAP measurements.

Results: Two patients (13%) had massive PE, and 13 (87%) had submassive PE refractory to standard medical therapy. There was 100% survival to discharge. Complications included transient hemoptysis (one patient) and asymptomatic tricuspid flail (one patient). Two patients required extracorporeal membrane oxygenation (ECMO) before thrombectomy. One patient had in-transit PE in the right atrium. One patient received and failed catheter-directed tissue plasminogen activator. The mean CTOI before intervention was 20.3 ± 1.9 and was 9.8 ± 4.8 postintervention. There was a mean decrease in CTOI of 10.5 ± 4.3 (P <0.0001). The mean preintervention RV/LV ratio was 1.6 ± 0.3 and was 1.0 ± 0.3 postintervention. Mean decrease in RV/LV ratio was 0.6 ± 0.5 (P = 0.001). The mean preintervention PAP was 28.2 ± 8.5 mm Hg, and the mean postintervention PAP was 21.2 ± 7.6 mm Hg. The mean decrease in PAP was 6.9 ± 6.9 mm Hg (P = 0.003). Seven (70%) of the 10 patients who had pre and post echocardiograms had abnormal RV function. Eighty-six percent of these patients regained normal RV function postthrombectomy.

Conclusions: There was a quantifiable and significant decrease in PE burden in patients who underwent thrombectomy using the Inari device. Also, there was significant decrease in right heart strain as evidenced by RV/LV ratio on CT and PAP. The majority of patients with decreased RV normalized postintervention.