Elsevier

Resuscitation

Volume 186, May 2023, 109775
Resuscitation

Clinical paper
Left-ventricular unloading in extracorporeal cardiopulmonary resuscitation due to acute myocardial infarction – A multicenter study

https://doi.org/10.1016/j.resuscitation.2023.109775Get rights and content

Abstract

Background

Guidelines advocate the use of extracorporeal cardio-pulmonary resuscitation with veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in selected patients with cardiac arrest. Effects of concomitant left-ventricular (LV) unloading with Impella® (ECMELLA) remain unclear. This is the first study to investigate whether treatment with ECMELLA was associated with improved outcomes in patients with refractory cardiac arrest caused by acute myocardial infarction (AMI).

Methods

This study was approved by the local ethical committee. Patients treated with ECMELLA at three centers between 2016 and 2021 were propensity score (PS)-matched to patients receiving VA-ECMO based on age, electrocardiogram rhythm, cardiac arrest location and Survival After Veno-Arterial ECMO (SAVE) score. Cox proportional-hazard and Poisson regression models were used to analyse 30-day mortality rate (primary outcome), hospital and intensive care unit (ICU) length of stay (LOS) (secondary outcomes). Sensitivity analyses on patient demographics and cardiac arrest parameters were performed.

Results

95 adult patients were included in this study, out of whom 34 pairs of patients were PS-matched. ECMELLA treatment was associated with decreased 30-day mortality risk (Hazard Ratio [HR] 0.53 [95% Confidence Interval (CI) 0.31–0.91], P = 0.021), prolonged hospital (Incidence Rate Ratio (IRR) 1.71 [95% CI 1.50–1.95], P < 0.001) and ICU LOS (IRR 1.81 [95% CI 1.57–2.08], P < 0.001). LV ejection fraction significantly improved until ICU discharge in the ECMELLA group. Especially patients with prolonged low-flow time and high initial lactate benefited from additional LV unloading.

Conclusions

LV unloading with Impella® concomitant to VA-ECMO therapy in patients with therapy-refractory cardiac arrest due to AMI was associated with improved patient outcomes.

Introduction

In the United States more than 350,000 patients suffered from out-of-hospital (OHCA) and 209,000 patients from in-hospital cardiac arrest (IHCA) in 2016, respectively.1 Survival after cardiac arrest following conventional cardiopulmonary resuscitation (CPR) is dismal, ranging from 6 to 22%.2, 3, 4, 5, 6, 7, 8, 9 In cases in which cardiac arrest is refractory to conventional CPR (i.e., failure to obtain return of spontaneous circulation [ROSC]), the use of extracorporeal CPR (ECPR) has been shown to be associated with improved survival rates and favorable neurologic outcomes compared to conventional CPR in observational studies and recent randomised clinical trials (RCTs).2, 4, 5, 7, 8, 9 Thus, ECPR has gained wider application in selected patients with a 10-fold increase in use between 2003 and 2014, and was advocated in recent guidelines.10, 11, 12, 13 ECPR is the implementation of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in a patient still being resuscitated. Patient selection, timing of cannulation (pre-hospital versus in-hospital), methods of cannulation and survival rates vary widely across institutions.14

Although VA-ECMO allows for full circulatory support, it is inherent to increased left ventricular (LV) pressure due to retrograde aortic perfusion with increased LV afterload, which may impede myocardial recovery, aggravate pulmonary oedema and cause ventricular arrhythmias or thrombotic events. Particularly in patients with cardiac arrest due to acute myocardial infarction (AMI) and an already severely impaired LV function, increased ECMO-induced cardiac afterload may cause additional harm.15, 16, 17 Moreover, ischaemic injury can be induced by the “watershed phenomenon” once the LV starts ejecting desaturated pulmonary blood into the systemic circulation.18, 19 In order to mitigate these negative sequelae, adjunct LV unloading with an Impella® micro-axial flow pump (Abiomed, Danvers, Massachusetts, USA) may be considered to provide continuous blood flow from the LV into the ascending aorta (ECMELLA). Thus, ECMELLA use is characterised by attenuated LV preload, diminished pulmonary wedge pressure, increased cardiac output and enhanced myocardial perfusion.20 There are presently no established recommendations for LV unloading during ECPR. Thus, the decision for Impella® implantation is left to the discretion of the ECPR team based on clinical, haemodynamic, radiologic and echocardiographic parameters. Recently, it has been shown that addition of Impella® to VA-ECMO may be associated with improved survival in patients with cardiogenic shock.21, 22, 23, 24, 25, 26 Additionally, ECMELLA use has recently been shown to reduce mortality in 18 patients with cardiac arrest of any cause.27 However, to the best of our knowledge, there are no data whether ECMELLA, being utilised as part of ECPR, is associated with survival benefits in selected patients with therapy-refractory cardiac arrest caused by AMI.

Therefore, the primary aim of this study was to evaluate the 30-day mortality rate of patients with therapy-refractory cardiac arrest due to AMI being treated either with VA-ECMO alone or with ECMELLA at three tertiary care centers over five years. Secondary endpoints included intensive care unit (ICU) and hospital length of stay (LOS), LV ejection fraction (LVEF) and post-procedural complications.

Section snippets

Study population

This study was performed at three tertiary care centers of the Charité – University Hospital in Berlin, Germany, and approved by the Institutional Review Board (protocol number: EA4/220/21). The publication adheres to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines (STROBE). The analyses were carried out within a consecutively enrolled cohort of adult patients who received treatment with ECPR after a therapy-refractory cardiac arrest (i.e., no ROSC at arrival

Patient characteristics

Between 2016 and 2021, 130 patients received ECPR treatment with VA-ECMO or ECMELLA, of which 95 met the inclusion criteria of the present study. A total of 57 (60%) patients received treatment with ECMELLA while 38 (40%) received treatment with VA-ECMO (Fig. 1, Table 1, Table 2). The Impella® therapy was started 95.7 minutes [IQR 43.6–185.7] after initiation of VA-ECMO therapy.

In the unmatched cohort, the average age in both treatment groups was 63.6 (±11.4) years with 78 (82.1%) patients

Discussion

In this multicenter cohort study among selected patients who received ECPR due to therapy-refractory cardiac arrest caused by AMI, ECMELLA treatment was associated with an improved survival compared to VA-ECMO therapy alone in both unmatched and PS-matched cohorts. The results remained robust in multiple sensitivity analyses. To the best of our knowledge, this is the first study showing that ECMELLA treatment was associated with improved survival after therapy-refractory cardiac arrest caused

Conclusions

In conclusion, in this PS-matched cohort of patients with ECPR during therapy-refractory cardiac arrest caused by AMI, we report that treatment with ECMELLA was associated with improved patient outcomes compared to VA-ECMO alone. Our data support current guideline recommendations on early evaluation of ECPR in well selected patients with therapy-refractory cardiac arrest. While there are several ongoing RCTs in the field of ECPR,43, 44, 45 a RCT is urgently needed to further evaluate the role

Sources of Funding

None.

Disclosures

None.

CRediT authorship contribution statement

Tharusan Thevathasan: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing – original draft, Visualization, Supervision, Project administration. Megan A. Kenny: Methodology, Validation, Formal analysis, Investigation, Writing – original draft, Visualization. Finn J. Krause: Validation, Formal analysis, Writing – original draft, Visualization. Julia Paul: Validation, Formal analysis, Writing – original draft, Visualization. Thomas Wurster:

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

None.

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