The benefits Abiomed's Impella RP System outweigh the risks of the device, but only if it is used for the currently approved indication in appropriately selected patients, according to FDA's latest letter about the device.
FDA said the latest interim results indicate a lower survival rate for the subgroup of post-approval study patients who would not have qualified for the premarket clinical studies compared to the premarket clinical study survival rate.
The agency reported that the most recent post-approval study report shows 12 out of the 42 patients (28.6%) survived to 30 days post device explant or hospital discharge, or to the start of longer-term therapy. In the premarket studies, the survival rate was 73.3%.
"The primary reason for the difference in survival outcome appears to be patient selection," FDA said in a letter to doctors.
For patients who would have met the enrollment criteria for the premarket studies, the survival rate was 64.3% (9 out of 14 patients). For the subgroup of patients who would not have qualified for the premarket studies, the survival rate was 10.7% (3 out of 28 patients).
Post-approval study patients who would not have qualified for the premarket clinical studies were more likely to have been in cardiogenic shock for longer than 48 hours, experienced a cardiac arrest, or suffered a pre-implant hypoxic or ischemic neurologic event before getting the Impella RP system implanted compared to the patients who would have met the enrollment criteria for the premarket clinical studies.
In April, FDA approved revised labeling for Abiomed's Impella RP System to include more information about patient selection and which patients may benefit the most from treatment with the device. In addition, the agency required Abiomed to make changes to the design of the post-approval study to include subgroup analyses and to establish a minimum number of patients in each subgroup. Details of the study protocol are posted on the FDA's Post-Approval Studies webpage.
The agency urged doctors on Tuesday to read and follow the revised labeling for the device, which includes a patient selection checklist to understand which patients may benefit most from treatment with the Impella RP System.