Mechanical Circulatory Support in High-Risk PCI: A Guide to Which, When, Who, and How

Identifying patients who require mechanical circulatory support (MCS) and then selecting the appropriate device can be difficult, prompting the Interventional Council of the American College of Cardiology to address the issue with a new algorithm aimed at easing decision making for interventional cardiologists in various scenarios.

The document, written by lead author Tamara Atkinson, MD (Oregon Health & Science University, Portland, OR), and colleagues on behalf of the council, discusses use of MCS devices in the settings of high-risk PCI, cardiogenic shock, and cardiac arrest. It also describes situations in which certain devices should be used over others depending on the level of hemodynamic support needed.

Although there is minimal evidence linking use of the devices to improved patient outcomes, operators often feel compelled to use them in their sickest patients.

“It can be challenging for interventional cardiologists to determine the need for mechanical circulatory support, given that cardiogenic shock and [high-risk PCI] patients represent a heterogeneous spectrum of clinical and anatomic disease that requires a tailored approach to improve individual hemodynamic parameters,” Dmitriy Feldman, MD (Weill Cornell Medicine, New York, NY), who was not involved in the paper, told TCTMD in an email.

“Furthermore,” he continued, “MCS devices should be viewed on a continuum of increasing hemodynamic support at the cost of more invasive vascular access and increased rate of complications, which can make it challenging to choose between MCS devices.”

MCS devices have been used for decades to stabilize patients with cardiogenic shock and provide hemodynamic support in patients undergoing high-risk PCI. Devices include the intra-aortic balloon pump (IABP) and newer ones such as the Impella line of ventricular assist devices (Abiomed), TandemHeart (TandemLife [formerly CardiacAssist]), and extracorporeal membrane oxygenation (ECMO), all of which provide better hemodynamic support compared with IABP.

Choosing the Right Device

In the May 9, 2016, issue of JACC: Cardiovascular Interventions, the authors outline an approach to using MCS. The first step, they say, is to promptly recognize patients with cardiogenic shock and identify patients with high-risk features for PCI.

Then, they say, a multidisciplinary heart team consisting of interventional cardiologists, cardiothoracic surgeons, critical care physicians, and advanced heart failure experts should be used to select the appropriate level of support required for a patient’s disease severity and the device needed to accomplish it, with the understanding that this might not be feasible in an emergency situation.

Going into the choice of MCS device should be the indications and contraindications for each device, the choice of access site based on the patient’s vasculature, and the level of operator experience with the available devices. The authors provide an algorithm to help guide this decision.

Generally, IABP is appropriate for lower levels of severity, with escalation to Impella, TandemHeart, or ECMO for sicker patients, according to the recommendations.

“With multiple MCS devices available, each institution must develop a strategy for the preferred MCS device for patients with adequate training of cardiac catheterization and ICU staff,” Atkinson and colleagues write, noting that there is a substantial learning curve when using these devices. “Each institution should become familiar with at least two levels of support including IABP and Impella or TandemHeart in order to provide safe and efficient delivery of care in patients with [high-risk PCI] and cardiogenic shock.”

Emphasis on Early Initiation

Commenting for TCTMD, Ajay Kirtane, MD, SM (NewYork-Presbyterian Hospital/Columbia University Medical Center, New York, NY), said the paper provides “a good summary of the overall scenarios for which interventionalists would consider or think to use a variety of support” and a useful description of available devices.

One area that could be emphasized more is the fact that initiating support early, rather than taking a wait-and-see approach, seems to be the paradigm when patients are determined to be candidates, he said, noting that many of these patients do not have the reserve to tolerate a delay.

“Even in the setting of, for instance, acute myocardial infarction, there’s been such an emphasis on opening the artery that I think if you don’t support the ventricle first, patients don’t do as well . . . unless you think to act first in terms of supporting the hemodynamics,” Kirtane said.

Another area that could have been emphasized more is the type of assessment needed to determine whether a patient should receive circulatory support, he said.

“You really need to look at the pulmonary artery pressures and do a full right-heart catheterization to assess the hemodynamics prior to doing what you do because then it becomes less formulaic,” he said. “If you have someone with a low [ejection fraction] and absolutely normal filling pressures, then that’s somebody who doesn’t necessarily need a support device.”

Asked why MCS is used so frequently considering the dearth of evidence supporting their effectiveness, Kirtane replied, “If it’s a life or death situation, you’re going to err on the side of supporting the patient as opposed to not. And one of the reasons why they’re used is because we can’t do trials of every single thing that there is out there.”

Feldman said additional studies are warranted. “Given insufficient randomized data comparing different MCS strategies in complex clinical scenarios, such as cardiogenic shock after cardiac arrest, further randomized controlled trials and registries are still needed to [help] clinicians make decisions in complex and gravely ill patient populations.”