Left ventricular unloading linked to lower mortality in patients with cardiogenic shock on extracorporeal membrane oxygenation

1. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) use in cardiogenic shock has been linked to a potentially harmful increase in left ventricular (LV) afterload. In this meta-analysis of observational studies, LV unloading therapies were associated with a lower observed mortality for patients with cardiogenic shock undergoing VA-ECMO.

2. Use of LV unloading therapies was linked to an increased risk of hemolysis but otherwise no difference in limb ischemia, bleeding, renal replacement, stroke, or other complications.

Evidence Rating Level: 1 (Excellent)

Study Rundown: The use of VA-ECMO is becoming a more common supportive intervention for many critically ill patients. In cardiogenic shock there is evidence that VA-ECMO may increase LV afterload and result in increased myocardial ischemia, worsened ventricular recovery, ventricular arrhythmias, thrombotic events, and other complications. It is unknown if LV unloading interventions such as intra-aortic balloon pump (IABP) can alleviate the risk of LV afterload increase with VA-ECMO. The current study is a systematic review of studies evaluating VA-ECMO in cardiogenic shock for which data on LV unloading strategies were available. The study found that use of LV unloading interventions was linked with a reduced mortality compared to patients without these strategies. There was an associated increase in hemolysis with LV unloading therapy but otherwise no increase in major complications.

The main strength of the study was the large observational cohort of patients. Limitations included retrospective nature of studies and predominant use of intra-aortic balloon pump as the LV unloading strategy.

Click to read the study in JACC

Relevant Reading: Venoarterial Extracorporeal Membrane Oxygenation in Cardiogenic Shock

In-Depth [systematic review and meta-analysis]: This study is a systematic review which included studies that examined the use of VA-ECMO in adults with cardiogenic shock if they provided data on mortality and use of LV unloading therapy. The specific unloading strategies included intra-aortic balloon pump (IABP) and percutaneous ventricular assist device (pVAD). Studies were excluded if the data was not available for the primary endpoint or LV unloading strategy was not clearly outlined.

A total of 17 observational studies were included, which examined 3997 patients with cardiogenic shock receiving VA-ECMO. A total of 1696 (42%) of patients had LV unloading strategies implemented, most commonly with IABP (91.7%). The overall mortality rate was lower for those with LV unloading (54% vs. 65%, risk ratio: 0.79; 95% confidence interval: 0.72 to 0.87; p < 0.00001). Hemolysis was higher for patients receiving LV unloading but otherwise complications were not significantly different between the two cohorts.

Image: PD

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