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The Impella Left Ventricular Assist Device: a Problematic Heart Pump Beset by Problems

Health Letter, June 2024

By Robert Steinbrook, M.D.
Director, Public Citizen's Health Research Group

The Impella heart pump is a miniaturized left ventricular assist device, the first model of which was marketed in the United States in 2008. Threaded into the heart through an artery in the leg, the catheter-based device pumps blood from the left ventricle (the main pumping chamber of the heart) into the aorta (which distributes oxygenated blood to the body). The device is used for short-term support of the heart in critical situations, such as for people with myocardial infarction (heart attack) complicated by cardiogenic shock and for those undergoing high-risk coronary angioplasty to open blockages in the blood vessels of the heart.

Worldwide, 300,000 Impella devices have been implanted in patients. Between 2013 and 2022, industry payments to U.S. physicians related to the device totaled tens of millions of dollars, ranking fifth of all medical devices for payments during this time period. For years, however, there have been important concerns about whether Impella devices have clinically meaningful survival benefits that outweigh their safety risks. These concerns were accentuated in December 2023 when Abiomed, the manufacturer, recalled the instructions for use for Impella because of the risks of the device perforating (cutting) the wall of the left ventricle in the heart; 66,390 devices in the were recalled in the United States.

In March 2024, the Food and Drug Administration (FDA) issued an information summary identifying the recall as Class 1, the most serious type. At the time, there had been 129 reported serious injuries, including 49 reports of death. The FDA criticized the manufacturer for not notifying the agency two years earlier, which delayed its warning to doctors and hospitals. In essence, the company revised the instruction manual and told cardiologists to be more careful. A cardiologist who has been critical of the devices responded: “I think cardiologists are already extremely careful…To say that you’re addressing 49 deaths by saying ‘be careful’ is not addressing the problem at all.”

In 2023, the FDA issued an information summary about another Class 1 recall of Impella devices because of the risk of motor damage to the heart pumps when used in patients who had undergone transcatheter aortic valve replacement. The manufacturer reported 30 complaints, 26 injuries and four deaths related to the issue.

Since 2008, various Impella models have been marketed in the United States and the FDA has allowed them to remain in use. Remarkably, it is still not known whether the benefits of the device outweigh the risks.

Coincidentally, soon after the FDA issued its recent alert, a randomized trial comparing the pump plus standard care with standard care alone in patients with myocardial infarction and cardiogenic shock was published. That trial took a decade to complete, required expansion from one to three European countries because of slow enrollment and still was only able to enroll 360 of the 1,211 patients who were screened.

The study found that death from any cause at 180 days occurred in 82 (45.8%) of the patients who received the pump and 103 (58.5%) of those in the standard-care group. For safety, however, the results were the opposite; 43 (24.0%) patients receiving the pump and 11 (6.2%) in the standard-care group experienced the composite safety end point, which included severe bleeding, inadequate blood supply to a leg or arm, hemolysis (destruction of red blood cells), device failure and worsening of aortic regurgitation (backflow of blood from the aorta to the left ventricle). Many patients required dialysis and related life-supporting treatments for renal failure — 75 (41.9%) patients in the heart pump group and 47 (26.7%) patients in the standard-care group.

The trial also had substantial limitations. Because the inclusion and exclusion criteria were strict, the findings likely apply to only a minority of patients with cardiogenic shock. The participating physicians were likely more skilled in implanting the device than most practicing cardiologists. And, inexplicably, although the trial lasted 10 years, length of patient survival beyond 180 days was not reported. Moreover, for patients undergoing high-risk coronary angioplasty to open blockages in the blood vessels of the heart — the other main reason the Impella device is used — there is still no evidence of effectiveness from a randomized trial comparing the devices to medical management.

If randomized controlled trials for medical devices such as the Impella were required before marketing, medical care could be based on robust evidence of benefit and harm, not physicians’ belief, influenced by industry marketing and largesse, that the benefits of a device outweigh the risks. Sixteen years after it was first marketed, the Impella device remains a problematic heart pump beset by problems and should only be used in people enrolled in a randomized, controlled trial comparing the heart pump with standard care.