Commentary: Left ventricle venting in extracorporeal membrane oxygenation: Comment on a proposed randomized trial.

Hiroo Takayama, MD, PhD, Serge Kobsa, MD, PhD, and Koji Takeda, MD, PhD

Proposed is a timely and well-designed randomized controlled trial comparing VA-ECMO alone to VA-ECMO + Impella CP device for LV venting in cardiogenic shock for enhancement of cardiac recovery.

See Article page 393.

Use of venoarterial extracorporeal membrane oxygenation (VA-ECMO) has become a common strategy of providing temporary support to patients in cardiogenic shock of different etiologies. Whereas VA-ECMO improves end-organ perfusion, coronary blood flow and unloads the right ventricle, it increases left ventricular (LV) afterload. In patients with severely reduced LV function, this can lead to LV distention, pulmonary edema, and even thrombotic complications in the LV and the aortic root due to stasis. In addition, it may hinder cardiac recovery by overstretching myocardial cells.

Despite the growing understanding of the importance of LV unloading in VA-ECMO patients based on both anecdotal evidence and a number of retrospective studies, there are no conclusive data supporting the routine use of LV venting in VA-ECMO patients. At our own high-volume center, we employ mechanical LV unloading with relative frequency, ranging from intra-aortic balloon pumps, percutaneous micro-axial ventricular assist devices (eg, Impella Heart Pump; Abiomed, Danvers, Mass), to surgical LV apical vents. However, as with most centers, given the inherent risks associated with these procedures, we introduce these mechanical LV unloading modalities in response to clinical indicators. In other words, this is a reactionary strategy as opposed to a proactive one.

We therefore welcome and applaud the initiation of a prospective Randomized trial of Early LV Venting using Impella CP for Recovery (REVERSE) in patients with cardiogenic shock managed with VA-ECMO (described in detail elsewhere). REVERSE is a nonindustry-sponsored, single-institution randomized controlled trial comparing VA-ECMO alone to VA-ECMO with percutaneously placed Impella CP device (Abiomed) for LV venting in cardiogenic shock.

It is going to be a bumpy ride. In REVERSE, the authors have chosen to focus on myocardial recovery while being able to complete enrollment in a reasonable amount of time, which has historically not been easy. To do so, patients with a range of heart failure etiologies are being included. In our experience, the chance of myocardial recovery is highly dependent on etiology, regardless of the use of LV venting., We suspect this may make it harder to interpret the results and to detect true effects of the intervention, especially given the proportionately low planned number of participants. Furthermore, wide variabilities in the acute illness as well as in ECMO management in these patients will introduce additional challenges.

This is indeed a timely and necessary study in the face of the current clinical equipoise that exists within the field. We are hopeful that the data generated will lead to evidence-based guidelines that will help improve the management these most complex and critically ill of patients.