The FDA yesterday said that interim data from a post-approval study of Abiomed‘s (NSDQ:ABMD) Impella RP heart pump system showed only a 17.4% survival rate, approximately 55% lower than the rate noted in the premarket study of the device.
The federal watchdog said that it is currently evaluating data from the study and that it will continue to monitor survival rates, but added that it still believes the system’s benefits outweigh the risks when used correctly.
In premarket clinical trials, results indicated a 73.3% survival rate to 30 days post device explant or hospital discharge, or to the start of the next longer term therapy, satisfying the study’s primary survival endpoint.
The post-market approval study of the device, which is slated to follow 60 patients through to one year, will have a similar primary endpoint of survival to 30 days post-explant, hospital discharge or the start of longer term therapy, the FDA said.
Interim results from the post-approval study, which currently has 23 patients, indicate a survival rate of only 17.4% of patients, or four of 23, have met the primary survival endpoint.
Upon analyzing the interim data, Abiomed said that the higher mortality rate may be primarily due to differences in pre-implant characteristics of patients, as 16 of the 23 patients in the post-approval study would “not have met the enrollment criteria for the premarket clinical studies,” according to the FDA release.
Patients in the post-approval study so far are more likely to have been in cardiogenic shock for longer than 48 hours, to have experienced an in-hospital cardiac arrest, have been treated with an intra-aortic balloon pump or suffered pre-implant hypoxic or ischemic neurological event when compared to patients in the premarket study, the FDA said.
“It is important to note that the Impella RP PAS and FDA’s evaluation into this issue are ongoing. We do not know the root cause for the high mortality rate, and the results are not adjusted for potential confounders,” the federal watchdog wrote in its posting.
The FDA warned healthcare providers to be aware of the differences in patient selection identified between the premarket and post-approval study cohorts when evaluating patient viability for therapy with the Impella RP.
Abiomed responded to the release by defending the Impella RP as the only device with FDA premarket approval for right side heart support, and saying that “proper use and timely implantation of the Impella RP increases survival with the potential for recovery of the right ventricle.”
The Danvers, Mass.-based company said that it proactively sent the interim data to physicians who use the Impella RP, including information on proper inclusion and exclusion criteria for patient selection.
Abiomed won clearance for the Impella RP in September of 2017, making it the only such device cleared for right heart failure.
Much like the company’s flagship Impella heart pump, the Impella RP is threaded into the heart via the femoral artery in the thigh. But unlike previous Impella models, all designed for the heart’s left ventricle, the Impella RP is designed to access the heart’s right ventricle via the vena cava.