Introduction
Acute pulmonary embolism (PE) can be stratified as high-risk or massive
PE, intermediate-risk or submassive PE, and low-risk or non-massive PE,
with nearly 300,000 deaths per year attributable to
PE1. Right ventricular dysfunction (RVD) and the
presence of hemodynamic instability are powerful predictors of poor
prognosis of patients with acute PE2. In particular,
patients with acute high-risk PE defined as cardiogenic shock and
systemic hypotension, are at particularly increased risk of early death,
and require emergency treatment to restore circulation. Overall,
in-hospital mortality rates for massive PE range from 25% for patients
with cardiogenic shock (CS), to 65% for those that required
cardiopulmonary resuscitation (CPR), while in-hospital mortality rate in
stable patients with PE was 8.1% 3.
Although systemic anticoagulation remains the cornerstone of therapy for
acute symptomatic pulmonary embolism, the morbidity and mortality
associated with high-risk PE and intermediate-high risk PE warrant
treatment beyond anticoagulation alone. More aggressive therapeutic
options include systemic intravenous thrombolysis (Class IB), surgical
embolectomy (Class IC) and catheter-directed thrombolysis needed (CDT)
(Class IIa) according to European Society of Cardiology
guidelines4.
However, the clinical course of high-risk PE can rapidly progress before
surgical or catheter-directed treatment. Many patients are not amenable
to reperfusion therapies or fail to improve after these treatments due
to major hemodynamic instability and cardiogenic shock. Based on the
ICOPER Registry, two-thirds of patients with massive PE did not receive
any thrombolysis or surgical embolectomy5. For those
patient group, veno- arterial extracorporeal membrane oxygenation
(VA-ECMO) is one of the most reliable and quickest way to decrease RV
overload, improve RV function and hemodynamic status, restore tissue
oxygenation and may be considered as either a bridge to reperfusion
therapy such as surgical embolectomy or CDT6.
The general aim of catheter-directed therapy in the setting of
hemodynamically compromised patients with acute PE is to debulk and/or
redistribute the obstructive clot rendering it less hemodynamically
significant. In recent years, interest has risen in a variety of
endovascular strategies based on catheter-based technologies for
thrombus removal in patients with high-risk PE. The EKOS EkoSonic
Endovascular System (EKOS, Boston Scientific, USA) is a catheter-based
system that uses high frequency, low-energy ultrasound waves to aid in
the delivery and uptake of thrombolytic agent within the clot.
Existing data regarding the utility of ECMO in the setting of high-risk
PE mainly come from case reports or small series(6-8). The impacts of VA-ECMO in conjunction with EKOS
acoustic pulse thrombolysis (APT) on survival have not been investigated
in massive PE. Therefore, we present a serie of patients with high risk
PE showing hemodynamic collapse that required cardiopulmonary
resuscitation, who were successfully treated with VA-ECMO as an adjunct
to APT.