Short-term Mechanical Circulatory Support: Take the Long View

Clinicians caring for patients who require short-term mechanical circulatory support (MCS) should take the long view in order to obtain the best outcomes, a new review asserts.

The document, published online today in the Journal of the American College of Cardiology, gathers the literature on what’s known about MCS, particularly the “emerging” Impella (Abiomed) percutaneous left ventricular assist device (LVAD), and explores how these devices are used in cardiogenic shock, right heart failure, and complex coronary interventions.

It covers wide ground, as the authors note, “from initial patient selection and access-site management to issues that arise during further intensive care treatment such as hemocompatibility, device positioning, and optimizing hemodynamics.”

Lead author Tim Balthazar, MD (University Hospitals Leuven, Belgium), told TCTMD that the paper was borne out of his own experiences as a cardiologist and intensivist. When it comes to MCS, he stressed, the end result depends not only on the device itself but also how the patient is managed thereafter.

“A lot of focus is on the early implantation, on the cath lab, but there’s not a lot of focus on the further management in the ICU. Our experience was that the final outcome was, say, 20% what happens in the cath lab and 80% what happens in the cardiac intensive care unit,” Balthazar explained.

Since reimbursement for Impella started few years back in Belgium, his center has been developing protocols to optimize management from start to finish, he said, and the resulting review “brings together both worlds.” Cardiologists may, for instance, be less familiar with PCO₂ gap, which is a marker of cardiac output versus demand, whereas intensivists are apt to be less familiar with the nuts and bolts of device positioning.

Behnam N. Tehrani, MD (Inova Heart and Vascular Institute, Falls Church, VA), commenting on the paper for TCTMD, said that it contains useful information and helps drive home the point that cardiologists should be part of the teams providing postoperative care. Tehrani was the lead author of a prior review calling for an “agnostic” approach to cardiogenic shock.

The new document, he said, “gives you an overall understanding of what the device is, how it works, what the troubleshooting mechanisms are,” while giving a “very balanced” description of Impella’s pros and cons.

Algorithms, Case Vignettes

To start, Balthazar et al highlight 13 key studies on Impella, most of which were published in the past few years.

Only two randomized clinical trials have tested percutaneous LVADs, they say, and much of the existing data comes from observational registries. Even less is known about ventricular assist devices geared toward right-heart support. Cardiogenic shock, with its rapid changes and high stakes, has proven particularly hard to study, as reported by TCTMD. There’s hope that the ongoing DanGer trial will provide some clarity on Impella’s performance in this setting.

The review quickly moves into advice that can be applied today, including who needs MCS and when.

“Patients are ideally selected based on their individual hemodynamic phenotypes, need for oxygenation, and relevant comorbidities,” the authors advise.

For Tehrani, the algorithm addressing cardiogenic shock is particularly helpful. It describes the timeline for MCS initiation as a patient progresses through the cardiogenic-shock stages created by the Society for Cardiovascular Angiography and Interventions, as well as how hemodynamic and respiratory factors call for the use of particular MCS devices. He also drew attention to the review’s case vignettes and tips for device positioning.

Figures like 5 and 6 should be laminated inside ICUs. It’s helpful . . . especially for physicians who may not have high levels of experience with these devices. Behnam N. Tehrani

Perhaps most important, though, are the two algorithms—shown in figures 5 and 6—that address how to cope with deteriorating hemodynamics and how to approach weaning, Tehrani stressed.

“To date there have not been any randomized clinical trials looking at best practices for device management beyond the cath lab. In the absence of [these] to inform management, best practices are best practices for each institution—it’s local,” he said, calling for research on escalation/weaning, complication management, and destination therapies.

Until trials can establish a “gold standard” for what should happen postimplantation, “I really think that figures like 5 and 6 should be laminated inside ICUs. It’s helpful . . . especially for physicians who may not have high levels of experience with these devices,” Tehrani suggested.

Balthazar, too, urged that consistency in care is key. This extends to the research setting, where the potential for RCTs like DanGer to prove positive may hinge on their protocols. “If you do not standardize how you treat the patients, well, okay you can put in the device, but then they will be treated in totally different ways for days and weeks,” he said. “And that will [influence] the final outcome I think much more than the device.”

Accumulating data will allow fine-tuning of algorithms, which in turn can be applied in trial design, Balthazar noted. “The Impella pump, it works. We know that it delivers the flow that you need. So the device works, that’s not a question. But to be able to help a patient, that device is only really a small part in the total care you give.”