Mechanical thrombectomy can improve cardiac index in patients with PE in subclinical shock
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A new study suggests that many patients with pulmonary embolism who present as hemodynamically stable may be in subclinical shock due to low cardiac index.
Moreover, mechanical thrombectomy may confer an immediate improvement in cardiac index for these patients, researchers reported at the Society of Critical Care Medicine Congress.
“There are certain limitations in the risk stratification scores that are available to us,” Bushra Mina, MD, FCCM, with the Lenox Hill PERT Team at Lenox Hill Hospital/Northwell Health, said during a presentation. “Most [patients with PE] will present in a hemodynamic normotensive state. However, research shows that there is a subset of patients who are hemodynamically stable and in a subclinical state of shock.”
Mina and colleagues aimed to assess the prevalence of low cardiac index in patients risk stratified using common schemes and also assess immediate on-table changes in cardiac index after mechanical thrombectomy.
Patients with PE were enrolled in FLASH, a prospective, multicenter registry evaluating outcomes after percutaneous mechanical thrombectomy with the FlowTriever System (Inari Medical). The FlowTriever System is a percutaneous mechanical thrombectomy system that rapidly extracts thrombus for on-table hemodynamic restoration without requiring thrombolytics.
Among the first 250 patients with PE enrolled in FLASH, the mean age was 61 years, 52.4% were men and half had bilateral PE.
Patients were risk stratified using current European Society of Cardiology (ESC) guidelines (n = 220 with cardiac index available), the simplified Pulmonary Embolism Severity Index (sPESI; n = 208 with cardiac index available) or Bova score (n = 201 with cardiac index available). Researchers measured cardiac index via right heart catheterization before and after thrombectomy. Patients were then categorized into low cardiac index and normal cardiac index groups, with the prevalence of low cardiac index determined for each risk group. Low baseline cardiac index was defined as less than 2 l/min/m2.
Risk stratification using the three tools varied, Mina said. The ESC guidelines identified 6.4% of patients as high risk, sPESI identified 84.6% as high risk and the Bova score identified 35.8% as high risk.
Low cardiac index was common, even in patients in the lower-risk tiers.
“An average of 20% of patients with PE in each of the low-risk tiers had low cardiac index prior to thrombectomy, regardless of the risk stratification method used,” Mina said.
Low cardiac index was present at baseline in 20% of patients with ESC intermediate-risk classification, 22% of patients with sPESI of 0 and 20% of patients with stage I or II Bova scores, according to the results.
The incidence of major adverse events at 48 hours, the primary endpoint of FLASH, was 1.4% among the first 500 patients enrolled in FLASH. There were no device-related deaths, Mina said.
In patients with low baseline cardiac index, thrombectomy with the FlowTriever resulted in a significant improvement in on-table low cardiac index, with an 18% increase (P < .0001) after thrombectomy. Mina said the average cardiac index reached nearly normal levels in these patients.
“The results from our study suggest a substantial portion of hemodynamically stable patients with pulmonary embolism may be at risk of hemodynamic collapse and a state of subclinical shock,” Mina said. “That subset of patients may benefit from mechanical thrombectomy and improvement in hemodynamics, and that ultimately will be translated into improvement in their outcome.”