Background: In patients with cardiogenic shock (CS), acute myocardial infarction (AMI) is the most common cause, and a percutaneous microaxial ventricular assist device (Impella, Abiomed, Danvers, MA) is a choice for temporary mechanical circulatory support. However, data are limited on complications and outcomes of Impella treatment in patients with CS with and without AMI. Methods and Results: Using nationwide prospective registry data in Japan, we included a total of 2047 patients with CS in whom the Impella devices were successfully placed between February 2020 and December 2021. Patients were divided into 2 groups according to the primary indication for the Impella use: AMI versus non‐AMI. The primary end point was a composite of in‐hospital all‐cause death and major complications. Of the 2047 patients, the Impella was indicated for AMI in 1337 (65.3%). In the group without AMI, myocarditis was the leading cause of CS. Patients with AMI‐CS were older and more likely to have cardiovascular risk factors than those with non‐AMI‐CS. The rates of in‐hospital mortality (46.0% versus 43.9%, P =0.38) and major complications (35.2% versus 34.7%, P =0.85) were similar between the 2 groups. Overall, multivariable analysis identified older age, higher body mass index, previous transient ischemic attack or stroke, out‐of‐hospital cardiac arrest, and the Impella 5.0 as factors significantly associated with the primary end point. Conclusions: The use of Impella in patients with and without AMI was related to similar clinical outcomes with high mortality and complication rates. Further studies are needed to identify patients who may benefit from the Impella devices in CS. Registration: URL: https://www.umin.ac.jp/english . Identifier: UMIN000033603.

The effect of prehospital factors on favorable neurological outcomes remains unclear in patients with witnessed out-of-hospital cardiac arrest (OHCA) and a shockable rhythm. We developed a decision tree model for these patients by using prehospital factors. Using a nationwide OHCA registry database between 2005 and 2020, we retrospectively analyzed a cohort of 1,930,273 patients, of whom 86,495 with witnessed OHCA and an initial shockable rhythm were included. The primary endpoint was defined as favorable neurological survival (cerebral performance category score of 1 or 2 at 1 month). A decision tree model was developed from randomly selected 77,845 patients (development cohort) and validated in 8650 patients (validation cohort). In the development cohort, the presence of prehospital return of spontaneous circulation was the best predictor of favorable neurological survival, followed by the absence of adrenaline administration and age. The patients were categorized into 9 groups with probabilities of favorable neurological survival ranging from 5.7 to 70.8% (areas under the receiver operating characteristic curve of 0.851 and 0.844 in the development and validation cohorts, respectively). Our model is potentially helpful in stratifying the probability of favorable neurological survival in patients with witnessed OHCA and an initial shockable rhythm.

Background: Lower primary percutaneous coronary intervention (PCI) volume is known to be associated with worse outcomes in patients with acute myocardial infarction (MI) at hospital level. The present study aimed to evaluate the relations of primary, elective, and total PCI volume and primary/total PCI volume ratio per hospital to in‐hospital mortality in patients with acute MI undergoing primary PCI. Methods and Results: Using a large nationwide administrative database, we included a total of 83 076 patients from 154 hospitals in Japan undergoing PCI for either acute MI or elective cases. Relations of annual procedural volumes for primary, elective, and total PCI to in‐hospital mortality after acute MI at hospital level were evaluated. The ratio of primary to total PCI volume per hospital was also assessed. The primary end point was the ratio of observed to predicted mortality. Of 83 076 patients, 26 913 (32.4%) underwent primary PCI for acute MI, among whom 1561 (5.8%) died during hospitalization. Overall, observed in‐hospital mortality after acute MI and observed/predicted mortality ratio were higher in hospitals with lower primary, elective, and total PCI volumes. Observed/predicted in‐hospital mortality ratio was higher in hospitals with low primary/total PCI volume ratio, even in those with high total PCI volume. Conclusions: Primary, elective, and total PCI volume at hospitals were inversely associated with in‐hospital mortality in patients with acute MI undergoing primary PCI. Lower ratio of primary to total PCI volume were related to higher in‐hospital mortality, suggesting primary/total PCI volume ratio as an institutional indicator of quality of care for acute MI.