7.3 / IAGS 2019
Session 7: Hemodynamics Session 1
Interventional and Surgical Therapies for Massive PE: What's PERTinent?
Problem Presenter: Herbert Aronow, MD
Statement of the problem
The number of hospitalizations for acute pulmonary embolism (PE) in the United States continues to climb and PE is now the third leading cause of cardiovascular mortality. Massive (also known as “high-risk”) PE, where there is associated hypotension, comprises only about 5% of all PE presentations but is associated with approximately a 30% mortality rate. Various therapeutic interventions are available, including systemic full-dose fibrinolysis, surgical embolectomy and catheter-directed therapy (CDT), but robust comparative safety and effectiveness data for these approaches are lacking.
Gaps in knowledge
While randomized controlled trials (RCTs) have demonstrated that systemic fibrinolysis reduces the incidence of mortality and recurrent PE, its benefit is offset by the increased risk of major bleeding, including intracranial hemorrhage. Meta-analyses of contemporary surgical embolectomy observational studies suggest that this intervention may be associated with reduced mortality as well. However, surgery is only an option for those with proximal PE and even when feasible, its potential benefits are countered by the attendant risks of surgery; furthermore, RCT data are lacking. More recently, CDT options have become available, two of which have FDA clearance for use in patients with PE. The EKOS Acoustic Pulse Thrombolysis catheter (EKOS, BTG), which is employed for ultrasound-assisted, low-dose catheter-directed fibrinolysis, may have greater potential benefit in the setting of more stable submassive (ie, intermediate-risk) than in massive PE, given that its therapeutic onset may not be immediate. In contrast, the FDA-cleared Flowtriever (Inari Medical) yields immediate results, which may make it a more attractive therapeutic option for patients with massive PE. Other non-FDA-cleared devices that are used in an off-label fashion in patients with massive PE include the Indigo Cat-8 (Penumbra) which is being evaluated in the Evaluating the Safety and Efficacy of the Indigo Aspiration System in Acute Pulmonary Embolism (EXTRACT-PE) study, the Angiovac (Angiodynamics), and the Aspire Max (Control Medical) catheters. Neither randomized studies nor comparative effectiveness data are available for any of these devices. Consequently (and not surprisingly), there is tremendous practice variability in the setting of massive PE.
Possible solutions and future directions
While randomized trials would address many unanswered questions surrounding the management of patients with massive PE, there are many challenges inherent in conducting such studies, including the relatively small number of patients presenting with this condition to any one institution and the array of available therapies, each of which would require separate evaluation. Absent such data, the most practical approach to treating patients with massive PE may be to standardize our treatment algorithms and to simultaneously collect national registry data to inform decision-making. To date, the most successful such initiative has been organized by the Pulmonary Embolism Response Team (PERT) Consortium. In the near future, Consortium leadership anticipates that its registry will include data on approximately 1500 patient episodes from more than 60 participating sites. The PERT Consortium and its leadership have advocated for a multidisciplinary approach to the management of submassive and massive PE that results in consensus-driven treatment recommendations. PERT treatment protocols support the decision-making process and are informed by existing data and expert opinion. Institutional participation in this initiative’s companion registry should be encouraged, as doing so will allow for real-time modification to treatment protocols based on registry safety and effectiveness observations.