Venoarterial Extracorporeal Membrane Oxygenation in High-Risk Pulmonary Embolism: A Case Series and Literature Review

Thrombolysis before venoarterial ECMO for high-risk pulmonary embolism: a retrospective cohort study

PURPOSE

Despite systemic thrombolysis, a few patients with high-risk pulmonary embolism (PE) remain hemodynamically unstable. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a considerable lifesaving therapy but systemic thrombolysis before cannulation could carry a high risk of hemorrhage and alter the prognosis.

METHODS

Between June 2012 and June 2023, we retrospectively analyzed from three intensive care units in Sorbonne University, ECMO-related complications and 90-day mortality for high-risk PE patients who received ECMO without previous systemic thrombolysis compared to those cannulated after systemic thrombolysis failure. Hospital discharge survivors were assessed for long-term health-related quality of life and echocardiographic evaluations.

RESULTS

72 high-risk PE patients [median age 48 (37-61) years, Simplified Acute Physiology Score II (SAPS II) 74 (60-85)] were placed on VA-ECMO for 5 (5-7) days. 31 (43%) patients underwent pre-ECMO thrombolysis (thrombolysis ECMO group, T +) compared to 41 patients (57%, no thrombolysis ECMO group, T-). There was more pre-ECMO cardiac arrest in the thrombolysis ECMO group (94% vs. 67%, p = 0.02). Ninety-day survival was not different between groups (39% vs 46%, log-rank test, p = 0.31). There was no difference in severe hemorrhages (61% vs 59%, p = 1). Twenty-five over 28 patients attended follow-up at a median time of 69 (52-95) months. Long-term quality of life was acceptable and none of them experienced chronic thromboembolic pulmonary hypertension.

CONCLUSIONS

Ninety-day survival and bleeding events rates did not differ in patients treated with VA-ECMO after systemic thrombolysis compared to those who were not. Recent systemic thrombolysis, as a single parameter, should not be considered as a contraindication for VA-ECMO in high-risk PE.

Extracorporeal Membrane Oxygenation for Pulmonary Embolism: A Systematic Review and Meta-Analysis

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) for high-risk pulmonary embolism (HRPE) with haemodynamic instability or profound cardiogenic shock has been reported. Guidelines currently support the use of ECMO only in patients with cardiac arrest or circulatory collapse and in conjunction with other curative therapies. We aimed to characterise the mortality of adults with HRPE treated with ECMO, identify factors associated with mortality, and compare different adjunct curative therapies.

METHODS

We conducted a systematic review and meta-analysis, searching four international databases from their inception until 25 June 2023 for studies reporting on more than five patients receiving ECMO for HRPE. Random-effects meta-analyses were conducted. The primary outcome was in-hospital mortality. A subgroup analysis investigating the outcomes with curative treatment for HRPE was also performed. The intra-study risk of bias and the certainty of evidence were also assessed. This study was registered with PROSPERO (CRD42022297518).

RESULTS

A total of 39 observational studies involving 6409 patients receiving ECMO for HRPE were included in the meta-analysis. The pooled mortality was 42.8% (95% confidence interval [CI]: 37.2% to 48.7%, moderate certainty). Patients treated with ECMO and catheter-directed therapy (28.6%) had significantly lower mortality (p < 0.0001) compared to those treated with ECMO and systemic thrombolysis (57.0%). Cardiac arrest prior to ECMO initiation (regression coefficient [B]: 1.77, 95%-CI: 0.29 to 3.25, p = 0.018) and pre-ECMO heart rate (B: -0.076, 95%-CI: -0.12 to 0.035, p = 0.0003) were significantly associated with mortality. The pooled risk ratio when comparing mortality between patients on ECMO and those not on ECMO was 1.51 (95%-CI: 1.07 to 2.14, p < 0.01) in favour of ECMO. The pooled mortality was 55.2% (95%-CI: 47.7% to 62.6%), using trim-and-fill analysis to account for the significant publication bias.

CONCLUSIONS

More than 50% of patients receiving ECMO for HRPE survive. While outcomes may vary based on the curative therapy used, early ECMO should be considered as a stabilising measure when treating patients with HRPE. Patients treated concurrently with systemic thrombolysis have higher mortality than those receiving ECMO alone or with other curative therapies, particularly catheter-directed therapies. Further studies are required to explore ECMO vs. non-ECMO therapies in view of currently heterogenous datasets.

Management of High-Risk Pulmonary Embolism: What Is the Place of Extracorporeal Membrane Oxygenation?

Pulmonary embolism (PE) is a common disease with an annual incidence rate ranging from 39-115 per 100,000 inhabitants. It is one of the leading causes of cardiovascular mortality in the USA and Europe. While the clinical presentation and severity may vary, it is a life-threatening condition in its most severe form, defined as high-risk or massive PE. Therapeutic options in high-risk PE are limited. Current guidelines recommend the use of systemic thrombolytic therapy as first-line therapy (Level Ib). However, this treatment has important drawbacks including bleeding complications, limited efficacy in patients with recurrent PE or cardiac arrest, and formal contraindications. In this context, the use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) in the management of high-risk PE has increased worldwide in the last decade. Strategies, including VA-ECMO as a stand-alone therapy or as a bridge to alternative reperfusion therapies, are associated with acceptable outcomes, especially if implemented before cardiac arrest. Nonetheless, the level of evidence supporting ECMO and alternative reperfusion therapies is low. The optimal management of high-risk PE patients will remain controversial until the realization of a prospective randomized trial comparing those cited strategies to systemic thrombolysis.