O ptimal timing to initiate Impella support in patients with postcardiac arrest cardiogenic shock due to acute myocardial infarction receiving percutaneous coronary intervention (PCI) remains unknown. Chatzis et al (1), published in the recent issue of Critical Care Medicine, demonstrated that pre-PCI initiation of Impella 2.5 support had an advantage in survival over the post-PCI initiation. In other words, the door to Impella time is more important than the door to balloon time. Several concerns have been raised.The timing to initiate Impella support was not randomized (1). Of note, Impella might have been implanted following PCI due to any unexpected adverse events-related hemodynamic deterioration. Baseline characteristics, probably obtained at admission, were not statistically different between the two groups (pre-PCI vs post-PCI), but background data obtained just before Impella initiation in the post-PCI group, such as hemodynamics and endorgan function, might be worse than the pre-PCI group.Left ventricular ejection fraction increased during the initial 72 hours when Impella was initiated before PCI, whereas it remained unchanged in the post-PCI group (1). Early cardiac unloading might have advantages in cardiac protection from ischemic attach and preservation of cardiac reserve. Further follow-up data including maximum creatinine kinase, troponin, B-type natriuretic peptide, and left ventricular end-diastolic diameter would strengthen the hypothesis.The prevalence of access site bleeding that required transfusion was higher in the pre-PCI group (1). Detailed mechanism remains uncertain, but Impellasupported PCI might have a higher risk of critical bleeding. Detailed data on the timing of critical bleeding (i.e., during PCI or post-PCI) and the magnitude of anti-coagulation therapy would be helpful to consider the strategy to manage bleeding. Relatively lower anti-coagulation might be beneficial for the pre-

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