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Interventional Therapies for Acute PE – What We Know and What We Don’t

December 27, 2019

Written by Bo Stubblefield

Spoon Feed
Emergency medicine docs should understand risk stratification of patients with acute PE as well as the risks, benefits, and gaps in evidence associated with interventional therapies.

Why does this matter?
The advent of catheter-directed lysis (CDL), catheter-based embolectomy, and the incorporation of a Pulmonary Embolism Response Team (PERT) are new, dynamic, interventional considerations for the management of massive PE as well as the more heavily debated intermediate-risk PE.

There is a LOT here. Let’s make like a lytic and break this down.

Risk Stratification
PE severity is divided into three main categories:

  1. Massive – hypotension (<90mmHg, but don’t forget “a drop of SBP >40mmHg for 15 min” counts)

  2. Submassive – no hypotension, but RV strain by echo, CT, or biomarkers (new ESC guidelines break this class into Intermediate-Low Risk and Intermediate-High Risk dependent on PESI score and elevation of troponin + RV dysfunction)

  3. Low Risk – not submassive. Low PESI score. Consider discharge home.

-Current risk stratification schemes have not been shown to improve patient outcomes.
-Most challenging is the intermediate-risk subgroup.
-Intermediate-risk PE patients at increased risk of decompensation include those with: elevated PESI or simplified PESI scores, severe PE-related functional impairment, and objective signs of severely diminished end-organ perfusion or stroke volume. Assuming low bleeding risk, such patients may benefit from thrombolysis or CDL.

CDL – catheter directed lysis

  • Current interventional therapies for acute PE include CDL or catheter-based embolectomy. Two devices: EKOSonic and FlowTriever have been cleared by the FDA for use in acute PE.

  • Use of CDL or catheter-based embolectomy in patients with intermediate-risk PE has, thus far, been correlated only with more rapid improvement of RV dysfunction than anticoagulation alone, not short- or long-term clinical or functional outcomes. CDL v. systemic thrombolysis is unknown.

  • Risks and benefits of systemic thrombolysis are closely counterbalanced in the intermediate-risk PE subgroup. Further, optimal dose and duration of systemic thrombolysis are unknown.

  • Indirect evidence supports lower rates of ICH and major bleeding in CDL compared to systemic thrombolysis.

  • No data support prevention of recurrent PE with CDL for treatment of acute PE.

Post-PE syndrome and chronic thromboembolic pulmonary hypertension (CTEPH)

  • A subset of patients with PE develop persistent symptoms and functional limitations; it is uncertain if systemic thrombolysis or CDL are associated with decreased post-PE syndrome.

  • It is unknown if CDL or embolectomy reduces the incidence of CTEPH.

Future Research Considerations

  • Effectiveness outcomes should include traditional clinical outcomes (death, hemodynamic decompensation, development of CTEPH) and patient-centered functional or quality of life measures.

  • Surrogate end points, including the short-term reduction in RV/LV ratio, should not be a proxy for mortality or other clinical outcomes in studies of patients with intermediate-risk PE.

PERT – PE Response Team

  • Available data demonstrate the use of CDL in 10-20% of patients with intermediate-risk PE.

  • Data on the influence of PERTs on the use of catheter-directed embolectomy are limited, but the use of CDL in hospitals with PERTs appears to be more common than the use of systemic thrombolysis.

  • It is unclear whether the PERT framework for acute PE care improves patient outcomes and is cost-effective.

Another Spoonful

Giri, J., et al., Interventional Therapies for Acute Pulmonary Embolism: Current Status and Principles for the Development of Novel Evidence: A Scientific Statement From the American Heart Association. Circulation, 2019. 140(20): p. e774-e801.

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Reviewed by Clay Smith

What are your thoughts?