The Current State of MCS for AMICS  

William O’Neill, MD, FACC, FSCAI, discusses the current state of mechanical circulatory support (MCS) for acute myocardial infarction cardiogenic shock (AMICS) with Bobbi Bogaev, MD, at SCAI 2022. Dr. O’Neill is director of the center for structural heart disease at Henry Ford Hospital in Detroit, MI, and co-primary investigator of the National Cardiogenic Shock Initiative (NCSI).

Why Are Institutional Protocols Important in Achieving Outcomes Seen in NCSI?

Even in busy practices, operators generally see only a few cases of AMICS each year. While well-defined protocols across the country help ensure systematic management and good outcomes in STEMI patients who are not in shock, Dr. O’Neill explains, “with shock it’s entirely different. And depending on where you go, what time of day, and what operator, you can have anything from nothing to use of ECMO… As leaders in cardiology, we have to systematize this across the country.” 

What Is the Rationale for Going Straight to ECMO in AMICS, and Is There Any Data to Support That?

Dr. O’Neill explains that there is no large, randomized data, and very little registry data, but quite a bit of experience, primarily in Europe, using ECMO in AMICS. While survival rates have been low, trial results from Germany are expected by the end of this year. Yet Dr. O’Neill states, “I would predict that it’s unlikely to be successful because biologically, using ECMO alone just doesn’t make sense in acute MI shock.” He contrasts this with SCAI stage C and D patients in NCSI, where survival outcomes are close to 80%.

What Are the Opportunities to Continue to Improve Outcomes in Hospitals Implementing NCSI?

“I think there’s an opportunity for more rapid identification of right ventricular dysfunction. I think a lot of doctors think that cardiogenic shock is just purely an LV problem, and it’s not; 40% of the time there is some RV involvement,” O’Neill explains. “In the CERAMICS protocol, we’re looking at a very early, aggressive escalation to try to normalize hemodynamics; to get the patients out of shock. And if they’re out of shock with just a pure left-sided support device, then that’s fine. But if they still have shock, meaning a CPO<0.6 for the left side, and a PAPi<1 for the right side, then we’re going to aggressively escalate, either with a larger left-sided device if it’s a left-sided problem, or with concomitant right-side device to improve RV failure. And we really think if we can do this aggressively, we can get survivals well over 80%.”

How Often Do Patients Escalate From Left-Sided or Biventricular Support to ECMO?

“I think it’s happening less frequently now, but I think what happened in the past is people would put in a left-sided Impella®, it wouldn’t be working very well, there’d be suction alarms, they’d say the device isn’t working, I’m just going to upgrade to ECMO. And that does work because usually it’s right ventricular dysfunction… It’s just that you don’t really need the oxygenator. Most of these patients are not hypoxic. And then you run into all the inflammatory responses and all the bleeding risk and vascular complications with ECMO. So we think that by earlier identification of RV dysfunction, you’ll minimize the need for further escalation.” 

“ECMO is not biologically plausible for treating acute MI because you do increase blood pressure, but at the expense of dramatically increasing afterload. And if you do that in the ventricle, you dramatically increasing infarct size... Now you could vent the ventricle, and people are using this ECpella combination, where you take blood out of the ventricle with an Impella catheter and still leave them on support. So that makes some biological sense, but ECMO alone is just not physiologically plausible.”

Why Is It Important to Engage a Heart Team Approach In AMICS?

Dr. O’Neill explains that in the NCSI program it was clear within 12-24 hours whether the patient was out of shock or in persistent shock. “If they’re in persistent shock at 12 hours, you’ve got to do something, otherwise the patients are not going to survive. That’s where the heart team comes in.” Dr. O’Neill explains that the best course of management for the patients can be determined by involving VAD surgeons, transplant surgeons, and interventional cardiologists in the decision-making.