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

It is unclear whether the impact of pre-reperfusion unloading on improving survival is sustained throughout all periods from the onset in patients with ST-segment-elevation myocardial infarction (STEMI). 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 complicated with cardiogenic shock and treated with Impella alone support were selected. Two cohorts were provided based on whether the onset-to-unloading time was < 6 hours. The patients were divided into 2 groups according to pre- or post-reperfusion unloading in each cohort. The primary outcome was a 30-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. Patients with pre-reperfusion unloading had a significantly higher 30-day survival rate than patients with post-reperfusion unloading (91% vs. 67%, p< 0.01) in the cohort with an onset-to-unloading time ≥6 hours, while patients with pre- and post-reperfusion unloading had similar 30-day survival rates (88% vs. 91%, p=0.64) 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 0.249 [95% confidence interval 0.070-0.889], p=0.03) in the onset-to-unloading time ≥6 hours cohort. In conclusion, pre-reperfusion LV unloading could be a crucial treatment to improve the short-term survival rate when the onset-to-LV unloading time was ≥ 6 hours.