- ECMO was considered a pathway to more aggressive interventions, including surgical embolectomy and catheter-directed thrombolysis, both of which were used more in the post-ECMO era
- ECMO, as part of a comprehensive approach to massive PE was linked to reduced mortality
Mortality rates associated with high-risk pulmonary embolism (PE) are as high as 70%. Extra-corporeal membrane oxygenation (ECMO) as part of aggressive treatment for high-risk PE increased the 30-day survival rate of patients by over 24%. The conclusion came from a Massachusetts General Hospital investigation published in Vascular Medicine that compared a pre-ECMO and post-ECMO care model for high-risk PE patients. The team also concluded that ECMO can reduce mortality rates in patients with massive PE.
Researchers conducted a single-center retrospective chart review of high-risk PE patients admitted with either PE and cardiac arrest or PE and shock from January 1, 1994 through December 31, 2014. A total of 60 patient cases were compared to discover treatment patterns and outcomes with 31 in the pre-ECMO era and 29 in the post-ECMO era. Patient characteristics were evaluated using t-tests and the chi-squared and Fisher’s exact tests for categorical variables and Wilcoxon rank sum tests for continuous variables.
Few baseline differences were apparent between pre- and post-ECMO patients. Across subjects, right ventricular dysfunction was present and blood pressure was managed with vasopressors in 88.2% and 92.5% of patients, respectively. However, notable differences found included an increased prevalence of coronary artery disease in the pre-ECMO era (16.1% vs 0%) and increased echocardiographic evidence of right ventricular dysfunction (96.4% vs 78.3%) in patients in the post-ECMO era.
In the post-ECMO era, ECMO was used in 13, or 44.8% of patients when more catheter-directed therapies were delivered. For example, all patients who received ECMO also received invasive PE-related treatment, either catheter-directed therapies or surgical embolectomy, and overall, there was greater utilization of catheter-directed compared to the pre-ECMO era. Following its review, the team found 30-day survival increased from 17.2% in patients who presented in the pre-ECMO era compared to 41.4% in the post-ECMO era (p=0.043).
In terms of how ECMO was delivered, all patients were cannulated on the first day of presentation with an average time from presentation to cannulation of 6 hours and an average length of support of 4 days. Nine patients received peripheral veno-arterial ECMO and four as central veno-arterial support. Also, in nine cases, ECMO was done prior to definitive therapy. In the other four cases, ECMO was started after surgical embolectomy.
Not surprisingly, settings for ECMO varied and included the operating room, emergency department, intensive care unit and cardiac catheterization laboratory.
While ECMO was not concluded as the cause of improved survival, its 24-hour availability was linked to improved outcomes. ECMO was considered a pathway to more aggressive interventions, including surgical embolectomy and catheter-directed thrombolysis, both of which are used more in the post-ECMO era. Emphasis was given to the importance of ECMO within the greater context of PE response teams that combine relevant specialists to streamline care when high-risk PE patients present. Such teams can use ECMO to deliver percutaneous coronary intervention with patients with acute coronary syndrome and cardiogenic shock and to directly treat cardiogenic shock.