Extracorporeal Life Support for Cardiogenic Shock With Either a Percutaneous Ventricular Assist Device or an Intra-Aortic Balloon Pump

Variability in triggers for mechanical left ventricular unloading in VA-ECMO: A literature search

BACKGROUND

Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO) is a means of supporting the lungs or the heart and lungs in patients with hemodynamic compromise that is refractory to conventional measures. VA-ECMO is most commonly deployed in a percutaneous fashion with femoral arterial and venous access. While VA-ECMO, particularly in a femoral-femoral configuration, provides both hemodynamic and ventilatory support, it also causes increased afterload on the left ventricle (LV) which in turn may result in LV distension (LVD). LV thrombus formation, ventricular arrhythmias, pulmonary edema, and pulmonary hemorrhage are clinical manifestations of LVD. LV unloading is a means of preventing LVD and its sequelae. If less invasive methods fail to achieve adequate LV unloading, invasive mechanical methods are pursued such as intra-aortic balloon pump counter-pulsation, atrial septostomy, surgical venting, left atrial cannulation, and percutaneous transvalvular micro-axial pump placement.

METHODS

We sought to review indicators of LVD, thresholds, and options for mechanical venting strategies. A Pubmed search was performed to identify current literature about LV unloading for VA ECMO. This was categorized and summarized to determine commonly reported thresholds for mechanical LV unloading.

RESULTS

Multiple physiologic and radiographic indicators were reported without uniformity. Common indicators included increased pulmonary artery catheter pressures, decreased Aortic Line Pulse Pressure, as well as multiple Echocardiographic, and radiographic indicators.

CONCLUSION

Although there has been significant interest in the topic, there is currently limited uniformity in thresholds for when to initiate and escalate mechanical LV unloading. While the method of LV unloading is an active area of investigation, the threshold for which to initiate invasive venting strategies is largely unexplored.

Different strategies in left ventricle unloading during venoarterial extracorporeal membrane oxygenation: A network meta-analysis

Background

Left ventricular (LV) overload is a frequent complication during VA-ECMO associated with poor outcomes. Many strategies of LV unloading have been documented but lack of evidence shows which is better. We conducted a network meta-analysis to compare different LV unloading strategies.

Methods

We searched databases for all published studies on LV unloading strategies during VA-ECMO. The pre-defined primary outcome was all-cause mortality.

Results

45 observational studies (34235 patients) were included. The Surface Under the Cumulative Ranking values (SUCRA) demonstrated that compared to no unloading strategy (15.4 %), IABP (73.8 %), pLVAD (60.8 %), atrial septostomy (51.2 %), catheter venting (48.8 %) were all associated with decreased all-cause mortality, in which IABP and pLVAD existed statistical significance. For secondary outcomes, no unloading group had the shortest VA-ECMO duration, ICU and hospital length of stay, and the lower risk of complications compared with unloading strategies. IABP was associated with reducing VA-ECMO duration, ICU and hospital length of stay, and the risk of complications (except for hemolysis as the second best) compared with other unloading strategies.

Conclusions

LV unloading strategies during VA-ECMO were associated with improved survival compared to no unloading, but the tendency to increase the risk of various complications deserves more consideration.

Mechanical circulatory support for cardiogenic shock: a network meta-analysis of randomized controlled trials and propensity score-matched studies

PURPOSE

Cardiogenic shock is associated with high mortality. In refractory shock, it is unclear if mechanical circulatory support (MCS) devices improve survival. We conducted a network meta-analysis to determine which MCS devices confers greatest benefit.

METHODS

We searched MEDLINE, Embase, and Scopus databases through 27 August 2023 for relevant randomized controlled trials (RCTs) and propensity score-matched studies (PSMs). We conducted frequentist network meta-analysis, investigating mortality (either 30 days or in-hospital) as the primary outcome. We assessed risk of bias (Cochrane risk of bias 2.0 tool/Newcastle-Ottawa Scale) and as sensitivity analysis reconstructed survival data from published survival curves for a one-stage unadjusted individual patient data (IPD) meta-analysis using a stratified Cox model.

RESULTS

We included 38 studies (48,749 patients), mostly reporting on patients with Society for Cardiovascular Angiography and Intervention shock stages C-E cardiogenic shock. Compared with no MCS, extracorporeal membrane oxygenation with intra-aortic balloon pump (ECMO-IABP; network odds ratio [OR]: 0.54, 95% confidence interval (CI): 0.33-0.86, moderate certainty) was associated with lower mortality. There were no differences in mortality between ECMO, IABP, microaxial ventricular assist device (mVAD), ECMO-mVAD, centrifugal VAD, or mVAD-IABP and no MCS (all very low certainty). Our one-stage IPD survival meta-analysis based on the stratified Cox model found only ECMO-IABP was associated with lower mortality (hazard ratio, HR, 0.55, 95% CI 0.46-0.66).

CONCLUSION

In patients with cardiogenic shock, ECMO-IABP may reduce mortality, while other MCS devices did not reduce mortality. However, this must be interpreted within the context of inter-study heterogeneity and limited certainty of evidence.

Left Ventricular Unloading With Impella Versus IABP in Patients With VA-ECMO: A Systematic Review and Meta-Analysis

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) use for circulatory support in cardiogenic shock results in increased left ventricular (LV) afterload. The use of concomitant Impella or intra-aortic balloon pump (IABP) have been proposed as adjunct devices for LV unloading. The authors sought to compare head-to-head efficacy and safety outcomes between the 2 LV unloading strategies. We conducted a search of Medline, EMBASE, and Cochrane databases to identify studies comparing the use of Impella to IABP in patients on VA-ECMO. The primary outcome of interest was in-hospital mortality. The secondary outcomes included transition to durable LV assist devices/cardiac transplantation, stroke, limb ischemia, need for continuous renal replacement therapy, major bleeding, and hemolysis. Pooled risk ratios (RRs) with 95% confidence interval and heterogeneity statistic I2 were calculated using a random-effects model. A total of 7 observational studies with 698 patients were included. Patients on VA-ECMO unloaded with Impella vs IABP had similar risk of short-term all-cause mortality, defined as either 30-day or in-hospital mortality- 60.8% vs 64.9% (RR 0.93 [0.71 to 1.21], I2 = 71%). No significant difference was observed in transition to durable LV assist devices/cardiac transplantation, continuous renal replacement therapy initiation, stroke, or limb ischemia between the 2 strategies. However, the use of VA-ECMO with Impella was associated with increased risk of major bleeding (57.2% vs 39.7%) (RR 1.66 [1.12 to 2.44], I2 = 82%) and hemolysis (31% vs 7%) (RR 4.61 [1.24 to 17.17], I2 = 66%) compared with VA-ECMO, along with IABP. In conclusion, in patients requiring VA-ECMO for circulatory support, the concomitant use of Impella or IABP had comparable short-term mortality. However, Impella use was associated with increased risk of major bleeding and hemolysis.

Veno-arterial extracorporeal membrane oxygenation with concomitant Impella versus concomitant intra-aortic-balloon-pump for cardiogenic shock

INTRODUCTION

The intra-aortic balloon pump (IABP) and Impella are left ventricular unloading devices with peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) in place and later serve as bridging therapy when VA-ECMO is terminated. We aimed to determine the potential differences in clinical outcomes and rate of complications between the two combinations of mechanical circulatory support.

METHODS

This was a retrospective, single institutional cohort study conducted in the intensive care unit (ICU) of Queen Elizabeth Hospital, Hong Kong. Inclusion criteria included all patients aged ⩾18 years, who had VA-ECMO support, and who had left ventricular unloading by either IABP or Impella between January 1, 2018 and October 31, 2020. Patients <18 years old, with central VA-ECMO, who did not require left ventricular unloading, or who underwent surgical venting procedures were excluded. The primary outcome was ECMO duration. Secondary outcomes included length of stay (LOS) in the ICU, hospital LOS, mortality, and complication rate.

RESULTS

Fifty-two patients with ECMO + IABP and 14 patients with ECMO + Impella were recruited. No statistically significant difference was observed in terms of ECMO duration (2.5 vs 4.6 days, p = 0.147), ICU LOS (7.7 vs 10.8 days, p = 0.367), and hospital LOS (14.8 vs 16.5 days, p = 0.556) between the two groups. No statistically significant difference was observed in the ECMO, ICU, and hospital mortalities between the two groups. Specific complications related to the ECMO and Impella combination were also noted.

CONCLUSIONS

Impella was not shown to offer a statistically significant clinical benefit compared with IABP in conjunction with ECMO. Clinicians should be aware of the specific complications of using Impella.