Interim results from a postapproval study of the AbioMed Impella RP system suggest a higher risk for death than the risk seen in premarket studies in patients treated with the temporary heart pump, the US Food and Drug Administration (FDA) said in a February 4 letter to cardiologists, cardiothoracic surgeons and transplant surgeons.
"Although the FDA is concerned about the high mortality rate from the interim PAS [postapproval study] results, we believe that when the device is used for the currently approved indication in appropriately selected patients, the benefits of the Impella RP system continue to outweigh the risks," the letter states.
The FDA granted premarket approval of the Impella RP system in 2017. The device is implanted centrally via peripheral access to help patients who require temporary emergency support of right ventricular function. Use of the device, which can be up to 14 days, requires patients to stay in the hospital.
In premarket studies, 44 of 60 patients (73.3%) survived to 30 days after the device was removed or after hospital discharge (whichever was longer), or to the start of next longer-term therapy, including heart transplant or implantation of a surgical right ventricular assist device.
Interim results of the postapproval study show a higher mortality rate, with only four of 23 (17.4%) patients meeting the same survival end points. A total of 60 patients will be followed in the postapproval study.
Although the FDA has yet to determine the root cause of the higher mortality rate, it could be related to differences in patient characteristics from the premarket studies.
Sixteen of the 23 patients enrolled in the postapproval study would not have met the enrollment criteria for the premarket studies. Specifically, before implantation of the Impella RP system, patients in the postapproval study were more likely to have been in cardiogenic shock for longer than 48 hours, to have experienced an in-hospital cardiac arrest, to have been treated with an intra-aortic balloon pump, or to have suffered a preimplant hypoxic or ischemic neurologic event.
"It's also important to note that the study population had additional health conditions that increased their risk of death compared to the premarket study population," the FDA said in statement.
"The study is doing exactly what postapproval studies are designed to do — provide more information about a device's benefit–risk profile by studying the performance and outcomes of device use in real-world clinical settings," said Jeff Shuren, MD, director of the FDA's Center for Radiological Devices and Health.
"We are thoroughly reviewing the data. Until we know more, we're giving healthcare providers recommendations to consider when making treatment decisions," said Shuren.
The FDA recommends that providers carefully consider information about the characteristics of patients enrolled in both the premarket and postmarket studies for this device when making treatment decisions about who might benefit from the Impella RP system and discuss the benefits and risks of the device with patients and their caregivers.
"It's important to note that while the data [are] concerning, the Impella RP system may be the best option for some patients requiring emergency treatment with a temporary heart pump," the FDA said.
"We're committed to early, transparent communications with healthcare providers and patients when safety signals emerge, and we'll continue to communicate about this issue as we learn more," said Shuren.
Adverse events or suspected adverse events related to the AbioMed Impella RP system should be reported through the FDA's MedWatch reporting system.
Cite this: Higher Than Expected Death Rate With Impella Heart Pump - Medscape - Feb 05, 2019.