A non-randomized study published in the American Heart Journal showed increased survival rates in patients with Impella device being used as the first support strategy for patients with acute myocardial infarction complicated by cardiogenic shock (AMICS) when invasive hemodynamic monitoring was used, and at centers with higher Impella implantation volume.
The Impella percutaneous ventricular assist device (PVAD) rapidly deploys mechanical circulatory support (MCS) in AMICS. The study was designed from a quality improvement (IQ) registry for U.S. patients with AMICS who received Impella devices. Dr. O’Neill and his colleagues examined data from the Abiomed funded IQ registry that included details on Impella device uptake and outcomes at 1,010 US hospitals from 2009 to 2016. Out of 46,949 patients, 15,259 had AMICS and received an Impella CP, Impella 2.5, or Impella 5.0 device. The data that was recorded included limited unidentified patient information, product performance, and survival to explantation.
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]“Practice patterns that consist of early initiation of MCS, before PCI, use of right heart monitoring, and greater institutional experience are associated with improved survival. It’s a very unique data set because it’s the kind of a comprehensive analysis of every Impella pump that was put in the United States from 2009 to 2016.” Dr. William W. ’Neill[/perfectpullquote]
The study reports, of the 15,259 patients with AMICS, 51% survived to explantation, and men had a significantly higher survival rate as compared with women (56.2% vs. 52.2%,p <0.001). Survival was also inversely associated with age. There was a significant difference between survival rates at the time of explantation across various settings.
Hospitals have been divided into ‘low volume’ (<4 patients/year with AMICS treated) and ‘high volume’ (>4 patients/year with AMICS treated). High-volume hospitals have a better survival as compared with low-volume hospitals (55.7% vs. 51.5%,p<0.001).
Additionally, the use of Impella as first-line treatment for AMICS was associated with a 59% survival rate as compared with 52% when used as a salvage strategy (p<0.001). The survival rate among patients who received hemodynamic monitoring was 63% as compared with 49% in those who did not (p<0.0001).
This study highlighted an interesting fact; Impella CP was linked to better survival versus the Impella 2.5. The reason most likely being the fact that Impella 2.5 provided 2.0 to 2.5 L of flow, whereas the upgraded Impella CP provided around 3.5 L of flow. Dr. O’ Neill remarked, “In patients that are in very profound shock or have a large body surface area, somebody that’s 80 kg or more, the 2.5 just really doesn’t provide enough forward cardiac support.”
Despite all these findings, there are still some concerns regarding a causal link between the volume sites and survival rates as the data comes from a manufacturer-sponsored study. In the future, a randomized clinical trial might be considered an option to answer these concerns.