Massive pulmonary embolism (MPE) is a serious condition affecting the pulmonary arteries and is difficult to diagnose, triage, and treat. The American College of Chest Physicians (AHA) and the European Society of Cardiology (ESC) have different classification approaches for PE, with the AHA defining three subtypes and the ESC four. Misdiagnosis is common, leading to delayed or inadequate treatment. The incidence of PE-related death rates has been increasing over the years, and mortality rates vary depending on the subtype of PE, with MPE having the highest mortality rate. The current definition of MPE originated from early surgical embolectomy cases and discussions among experts. However, this definition fails to capture patients at the point of maximal benefit because it is based on late findings of MPE. Pulmonary Embolism Response Teams (PERTs) have emerged as a fundamental shift in the management of MPE, with a focus on high-risk and MPE cases and a goal of rapidly connecting patients with appropriate therapies based on up-to-date evidence. This review highlights the challenges in diagnosing and managing MPE and emphasizes the importance of PERTs and risk stratification scores in improving outcomes for patients with PE.

Treatment of massive pulmonary embolism (MPE) is controversial, with mortality rates ranging from 25% to 65%. Patients commonly present with profound shock or cardiac arrest. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is increasingly being used as a form of acute cardiopulmonary support in critically ill patients. We reviewed our institution\'s pulmonary embolism response team experience using VA-ECMO for patients presenting with advanced shock and/or cardiac arrest from MPE.
From March 2017 to July 2019 we retrospectively reviewed 17 consecutive patients at our institution with MPE who were placed on VA-ECMO for initial hemodynamic stabilization.
The mean patient age and body mass index was 55.8 years and 31.8, respectively. Ten of 17 patients (59%) required cardiopulmonary resuscitation before or during VA-ECMO cannulation. All patients had evidence of profound shock with a mean initial lactate of 8.95 mmol/L, a mean pH of 7.10, and a mean serum creatinine of 1.78 mg/dL. Seventeen of 17 cannulations (100%) were performed percutaneously, with 41% (n = 7) of patients placed on VA-ECMO while awake and using local analgesia. Five of 17 patients (29%) required reperfusion cannulas, with 0% incidence of limb loss. Overall survival was 13 of 17 patients (76%), with causes of death resulting from anoxic brain injury (n = 2), septic shock (n = 1), and cardiopulmonary resuscitation-induced hemorrhage from liver laceration (n = 1). In survivors, 12 of 13 patients (92%) were discharged without evidence of neurologic insult. The median duration of the VA-ECMO run for survivors was 86 hours (range, 45-218 hours). In survivors, the median length of time from ECMO cannulation to lactate clearance (<2.0 mmol/L) was 10 hours and the median length of time from ECMO cannulation to freedom from vasopressors was 6 hours. Three of 13 patients (23%) required concomitant percutaneous thrombectomy and catheter-directed thrombolysis to address persistent right heart dysfunction, with the remaining survivors (77%) receiving VA-ECMO and anticoagulation alone as definitive therapy for their MPE. The median intensive care and hospital length of stay for survivors was 9 and 13 days, respectively.
VA-ECMO was effective at salvaging highly unstable patients with MPE. Survivors had rapid reversal of multiple organ failure with ECMO as their primary therapy. The majority of survivors required ECMO and anticoagulation alone for definitive therapy of their MPE.