Effectiveness of systemic thrombolysis on clinical outcomes in high-risk pulmonary embolism patients with venoarterial extracorporeal membrane oxygenation: a nationwide inpatient database study

Integration of Extracorporeal Membrane Oxygenation into the Management of High-Risk Pulmonary Embolism: An Overview of Current Evidence

High-risk pulmonary embolism (PE) refers to a large embolic burden causing right ventricular failure and hemodynamic instability. It accounts for approximately 5% of all cases of PE but contributes significantly to overall PE mortality. Systemic thrombolysis is the first-line revascularization therapy in high-risk PE. Surgical embolectomy or catheter-directed therapy is recommended in patients with an absolute contraindication to systemic thrombolysis. Extracorporeal membrane oxygenation (ECMO) provides respiratory and hemodynamic support for the most critically ill PE patients with refractory cardiogenic shock or cardiac arrest. The complex management of these individuals requires urgent yet coordinated multidisciplinary care. In light of existing evidence regarding the utility of ECMO in the management of high-risk PE patients, a number of possible indications for ECMO utilization have been suggested in the literature. Specifically, in patients with refractory cardiac arrest, resuscitated cardiac arrest, or refractory shock, including in cases of failed thrombolysis, venoarterial ECMO (VA-ECMO) should be considered, either as a bridge to percutaneous or surgical embolectomy or as a bridge to recovery after surgical embolectomy. We review here the current evidence on the use of ECMO as part of the management strategy for the highest-risk presentations of PE and summarize the latest data in this indication.

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.

Neurological outcomes and reperfusion strategies in out-of-hospital cardiac arrest patients due to pulmonary embolism who underwent venoarterial extracorporeal membrane oxygenation: A post-hoc analysis of a multicenter retrospective cohort study

INTRODUCTION

This study aimed to evaluate the effect of different reperfusion strategies on neurological outcomes in patients with pulmonary embolism who received venoarterial extracorporeal membrane oxygenation (VA-ECMO) for out-of-hospital cardiac arrest (OHCA).

METHODS

This was a post-hoc analysis of a multicenter retrospective cohort study conducted in 36 institutions in Japan over six years. We included patients who underwent VA-ECMO and were diagnosed with pulmonary embolism caused by OHCA. Neurological outcomes were evaluated on the basis of the cerebral performance category at hospital discharge. We also assessed the association between reperfusion strategies and successful separation from ECMO.

RESULTS

Among the 78 included patients, approximately half were successfully weaned from ECMO. Hospital mortality and favorable neurological outcomes at hospital discharge were 60.3% and 17.9%, respectively. Thirty-one patients (39.7%) underwent reperfusion strategies after ECMO, including 13 who received systemic thrombolytic therapy and 18 who underwent mechanical reperfusion strategy. After adjusting for prespecified covariates using the competing risk model, reperfusion strategies increased ECMO separation rate (systemic thrombolytic therapy: subdistribution hazard ratio [sHR] 2.24, 95% confidence interval [CI] 1.21-4.17, P = 0.011; mechanical reperfusion strategy: sHR 1.70, 95% CI 0.86-3.41, P = 0.129) compared with anticoagulation therapy alone, whereas higher cardiac Sequential Organ Failure Assessment score decreased ECMO separation rate (sHR 0.81, 95% CI 0.67-0.97, P = 0.020).

CONCLUSIONS

Favorable neurological outcomes were observed in less than 20% of patients with OHCA due to pulmonary embolism undergoing ECMO. Reperfusion strategies may be associated with shorter ECMO durations in these patients.

CLINICAL TRIAL REGISTRATION

https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000041577 (unique identifier: UMIN000036490).

Trends in Treatment Patterns and Outcomes of Patients With Pulmonary Embolism in Japan, 2010 to 2020: A Nationwide Inpatient Database Study

Background The impact of major changes in the treatment practice of pulmonary embolism (PE), such as limited indications for systemic thrombolysis and the introduction of direct oral anticoagulants, is not well documented. This study aimed to describe annual trends in the treatment patterns and outcomes in patients with PE. Methods and Results Using the Japanese Diagnosis Procedure Combination inpatient database from April 2010 to March 2021, we identified hospitalized patients with PE. Patients with high-risk PE were defined as those admitted for out-of-hospital cardiac arrest or who received cardiopulmonary resuscitation, extracorporeal membrane oxygenation, vasopressors, or invasive mechanical ventilation on the day of admission. The remaining patients were defined as patients with non-high-risk PE. The patient characteristics and outcomes were reported with fiscal year trend analyses. Of 88 966 eligible patients, 8116 (9.1%) had high-risk PE, and the remaining 80 850 (90.9%) had non-high-risk PE. Between 2010 and 2020, in patients with high-risk PE, the annual proportion of extracorporeal membrane oxygenation use significantly increased from 11.0% to 21.3%, whereas that of thrombolysis use significantly decreased from 22.5% to 15.5% (P for trend <0.001 for both). In-hospital mortality significantly decreased from 51.0% to 43.7% (P for trend=0.04). In patients with non-high-risk PE, the annual proportion of direct oral anticoagulant use increased from 0.0% to 38.3%, whereas that of thrombolysis use significantly decreased from 13.7% to 3.4% (P for trend <0.001 for both). In-hospital mortality significantly decreased from 7.9% to 5.4% (P for trend <0.001). Conclusions Substantial changes in the PE practice and outcomes occurred in patients with high-risk and non-high-risk PE.