Impella heart pump reduces risk of acute kidney injury in high-risk patients

Research from the University of Louisville has found that the Abiomed Impella 2.5 heart pump helps reduce the risk of acute kidney injury—even in patients with preexisting kidney disease—when physicians are trying to complete a high-risk percutaneous coronary intervention (HRPCI).

The study, published in Circulation Research, is building off earlier data from the PROTECT II study, a randomized clinical trial that found kidney injury rates were lower when more contrast material was used during HRPCI.

The work was led by Michael P. Flaherty, MD, an associate professor of medicine and physiology at the University of Louisville School of Medicine. The findings from his study add to a growing body of evidence that Impella products are safe, effective and, in some cases, necessary when completing HRPCI.

“The challenge for us was to do something for high-risk patients that wouldn’t lead to the type of acute kidney injury that we were seeing in the past,” Flahery said in an interview. “So we decided, based on our earlier findings, that the kidney function seemed to be preserved when we used the Impella device.”

This isn’t the only recent research on Abiomed products that has yielded positive results and strengthened the reputation of the brand’s devices. At this year’s American College of Cardiology’s 66th Annual Scientific Sessions, a study presented showed that proper use of the Impella CP pump can reduce mortality rates among cardiogenic shock patients.

In Flahery’s retrospective, single-center study, researchers examined the procedure and clinical outcomes for 230 patients with an ejection fraction of 35 percent or less before undergoing HRPCI. Half of them were supported with the Impella 2.5 and were compared with a control group of 115 patients undergoing HRPCI without Impella.

The patients in the study had severely depressed heart function, and half had baseline kidney disease.

Results showed that patients treated with the Impella device were more likely to develop comorbidities at baseline, including left main and three-vessel disease, and lower ejection fraction. However, despite the increased risk factors, only 5.2 percent of the patients treated with Impella developed acute kidney injuries after the procedure, compared to the 27.8 percent in the control group. Less than 1 percent of patients treated with Impella required hemodialysis, while 6.1 percent of control patients needed it.

Additionally, when the researchers controlled for heart function and underlying kidney disease, results showed that patients who already struggled with depressed heart function and worsening kidney disease still were protected against kidney injury.

“What we gleaned from this is that in this very high-risk population of patients who normally would have a 28 percent incidence of acute kidney injury, we reduced it to 5 percent with the Impella device,” Flaherty said.

Though the results provide evidence that the Impella device solely plays a role in how much damage occurs to the kidneys, Flaherty said his study did not reveal exactly what the device does in order to prevent it. He plans to explore it future studies, but hypothesizes that the Impella flushes out contrast that normally gets stuck in the kidneys.

“We know that Impella improves microcirculation to near normal levels when it’s used in human and animal models," he said. "We have to assume ostensibly that because it does that, it inhibits reduce kidney flow during these very risky procedures where kidney flow is actually perturbed quite a bit. In doing so, it reduces the likelihood of injuring the kidney and also prevents the stagnation of this contrast material in the smallest part of the kidney. So we feel that it must wash out this material and not let it stagnate in the kidneys.”

In addition to analyzing exactly how the Impella works to decrease kidney damage, Flaherty said he also wants to explore how results would present if future trials were randomized and took place at multiple centers. He also plans to test the efficacy of the Impella CP device in a similar study. But in the meantime, he said the current findings can help guide physicians on how to better treat these types of patients.

“These data are going to help us better [serve] patients in this very high-risk patient population,” Flaherty said. “It’s going to allow operators to push the envelope a little more in terms of completely treating the patient in one setting, which is the best thing for the patient.”