Acute outcomes for the full US cohort of the FLASH Mechanical Thrombectomy Registry in pulmonary embolism
Reported from TCT 2022
Waqar Ahmed provides his take on the FLASH Mechanical Thrombectomy Registry which was presented by Catalin Toma at TCT 2022.
The article was simultaneously published in the EuroIntervention Journal: Acute Outcomes for the Full US Cohort of the FLASH Mechanical Thrombectomy Registry in Pulmonary Embolism. EuroIntervention, C. Toma et al. DOI: 10.4244/EIJ-D-22-00732
Why this study? – the rationale/objective
Pulmonary embolism is a serious medical condition that carries a mortality of 6.5%. While treatment for intermediate risk pulmonary embolism is anticoagulation and thrombolysis is recommended for high risk pulmonary embolism. The safety of mechanical thrombectomy in pulmonary embolism has not been shown. This is the largest registry of patients with pulmonary embolism treated with interventional catheter-directed thrombectomy. The most important aim is to demonstrate the safety of this procedure using the FlowTriever System (Inari Medical, Irvine, CA).
How was it executed? – the methodology
Prospective investigators reported multi-centre registry of 800 patients with pulmonary embolism across the USA, of these almost 77% were intermediate-high risk. At this presentation, clinical follow-up is presented at 48 hours and 30 days. The decision to use mechanical thrombectomy was at the discretion of the treating physician. The primary endpoint was major adverse events at 48 hours. Secondary endpoints were hemodynamic assessments.
What is the main result?
800 patients in the United States were enrolled. Mean age 61 years and 46% were women. Those with cancer or history of malignancy comprised 29% of the cohort. Bilateral thrombus was present in 52% and a two-thirds of the patient had concomitant deep vein thrombosis.
The primary endpoint of major adverse events occurred in 1.8% of the patients at 48 hours. The all-cause mortality rate was 0.8% at 30 days with no device-related deaths. There was significant improvement in mean pulmonary artery pressure, cardiac index, right ventricular function and heart rate.
Critical reading and the relevance for clinical practice
This is the largest prospective registry of mechanical thrombectomy for pulmonary embolism. The current European guidelines recommend anticoagulation for pulmonary embolism and thrombolytic therapy for high-risk pulmonary embolism. This is due to lack of evidence for the use of mechanical devices for pulmonary embolism. This registry is a step towards filling this gap. The primary aim of this study was to demonstrate the safety of the large bore device for mechanical thrombectomy. This aim was achieved.
In an interview, Dr Toma the lead author commented that the biggest satisfaction is seeing the patients’ immediate hemodynamic improvement on the table. The alternative is anticoagulation or thrombolysis with intensive care unit care and improvement may take hours.
The next step is to demonstrate the efficacy of this treatment over the current standard of care. There are ongoing randomized clinical trials which will compare mechanical thrombectomy with catheter directly thrombolytic therapy for the treatment of intermediate to high-risk pulmonary embolism. We need to further define which patients benefit from mechanical thrombectomy versus anticoagulation. Significant expansion of pulmonary thrombectomy services will be needed if efficacy over current standard of care is shown. Dr Toma indicated that this will be a relatively easy procedure for most interventional cardiologists and for sick patients they are on the most appropriate path for ECMO support should that be needed.
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