Impact of Pre-reperfusion Left Ventricle Unloading on ST-segment-elevation Myocardial Infarction According to the Onset-to-Unloading Time

Background: Impella in the left ventricle (LV) with delaying reperfusion reduces the infarction size in animal models. However, the onset-to-unloading time in real-world practice can frequently be longer than that in animal experiments. It is unclear whether the impact of pre-reperfusion Impella use is sustained throughout all periods from the onset. This study aimed to evaluate the association between the onset-to-unloading time and the effect of pre-reperfusion Impella on the survival of patients with ST-segment-elevation myocardial infarction (STEMI). Methods: This study is a post-hoc analysis of the J-PVAD registry. Among all patients registered in J-PVAD between February 2020 and December 2021, patients with STEMI and treated with Impella alone support were selected. Two cohorts were provided based on whether the onset-to-unloading time was less than 6 hours. The patients were divided into two groups according to pre- or post-reperfusion use of Impella in each cohort. The primary outcome was an 80-day survival rate. The independent factors of survival were identified with a multivariable Cox proportional hazard regression analysis after adjusting for the variables that were statistically significant in the univariable analysis. Results: Patients with pre-reperfusion unloading had a significantly higher 80-day survival rate than patients with post-reperfusion unloading (81.6% vs. 59.5%, p=0.02) in the cohort with an onset-to-unloading time ≥6 hours, while patients with pre- and post-reperfusion unloading had similar 80-day survival rates (85.3% vs. 91.2%, p=0.38) in the cohort with an onset-to-unloading time <6 hours. A multivariable analysis revealed that pre-reperfusion use of Impella was an independent factor of survival (hazard ratio 0.184 [95% confidence interval 0.045-0.746], p=0.02) in the onset-to-unloading time ≥6 hours cohort. Conclusions: Pre-reperfusion LV unloading could be a crucial treatment to improve the short-term survival rate when the onset-to-LV unloading was more than 6 hours. ### Competing Interest Statement Masami Nishino receives donations from Abbott Medical Japan, Boston Scientific Japan, Medtronic, Japan Lifeline. However, the donation is not for this study. The other authors report no conflict. ### Clinical Trial The Universal Hospital Medical Information Network (UMIN) Clinical Trial Registry (ID: UMIN 000033603) ### Funding Statement This study was funded by a donation from Abiomed Japan and self-financing by the Japan VAD Council, IMPELLA Committee. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Central Institution Review Board at Osaka University. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Raw data were generated at the Japan VAD Council, IMPELLA Committee. Derived data supporting the findings of this study are available from the corresponding author on request.