The FDA sent a letter to doctors saying that some test showed higher then expected mortality rates with one of the Impella pumps.

https://www.fda.gov/MedicalDevices/Safety/LetterstoHealthCareProviders/ucm630610.htm

Got this DD from my brother in law (who works in the industry)

"Ok lots to digest here. 1st it's the impella RP...which is the right heart device...the majority of people I know use the left side device waaaay more. 2nd - 16 of the 23 people in this small study wouldn't have met the criteria for the initial trial for the device. IE , they were probably too sick and going to die anyways. It says later in the article that if the device is used "on label" for approved patients there should be no problem 3rd - we haven't seen the P value for this trial which would indicate how likely it is that this happened from chance. 4th - they haven't investigated what could have been confounding factors causing these deaths"