Optimal Timing of Microaxial Flow Pump(Impella CP) in AMI-related Cardiogenic Shock

• Study Objectives: To determine whether routine pre-percutaneous coronary intervention (PCI) Impella CP reduces the composite of all-cause death within 30 days after randomization or refractory shock within 48 hours after index PCI compared with revascularization first and selective post-PCI Impella CP in patients with acute myocardial infarction-related cardiogenic shock (AMICS) for whom Impella CP support is planned.
• Study Background: AMICS is among the most lethal complications of acute myocardial infarction (AMI). It occurs in approximately 5-10% of patients with AMI, and short-term mortality remains approximately 40-50% despite rapid reperfusion and advances in critical care. Early culprit-vessel revascularization has been central to AMICS care, yet shock and multiorgan failure frequently persist after technically successful PCI.

Vasopressors and inotropes are often required to maintain blood pressure and organ perfusion, but high doses or prolonged use can increase myocardial oxygen demand, provoke arrhythmia, and worsen peripheral vasoconstriction. Routine mechanical circulatory support for unselected AMICS populations has not consistently improved outcomes.

Impella CP is a percutaneous transvalvular microaxial flow pump inserted through the femoral artery. It transfers blood from the left ventricle to the ascending aorta, supporting systemic circulation while unloading the left ventricle and potentially reducing filling pressure, wall stress, and myocardial oxygen demand. The randomized DanGer-Shock (Danish Cardiogenic Shock) trial established a potential survival benefit in selected AMICS patients while reinforcing the need to optimize use and limit device-related harm.

The 2025 American guideline for the management of acute coronary syndromes states that, in selected patients with ST-segment elevation myocardial infarction (STEMI) and severe or refractory cardiogenic shock, the use of a microaxial flow pump may be reasonable to reduce the risk of death. However, in the DanGer-Shock trial, randomization concerned the use of the Impella CP, whereas the timing of device insertion, before or after PCI, was neither randomized nor specified by the study protocol. Accordingly, the guideline also acknowledges that the preferred timing of Impella insertion remains unclear. Therefore, the results of DanGer-Shock alone do not establish the superiority of pre-PCI over post-PCI insertion, and a randomized trial directly comparing these two strategies is warranted.

This study will randomly compare the clinical efficacy and safety of a routine pre-PCI Impella CP insertion strategy with a PCI-first strategy involving selective Impella CP insertion. It will determine whether the potential benefits of early left ventricular unloading and hemodynamic stabiliation outweigh the risks associated with pre-emptive device insertion in all patients, or whether restricting Impella CP use to patients with persistent shock after initial coronary revascularization can reduce unnecessary device use and related complications while providing comparable or superior clinical outcomes. This study has important clinical significance because it will address a key unresolved question following the DanGer-Shock trial, moving beyond "whether to use the Impella CP" to "in whom and when it should be used". By incorporating the potential benefit of avoiding device use in patients whose shock resolves with PCI alone, while simultaneously evaluating the risks of delaying circulatory support in those who require early mechanical support, this study is expected to provide a more individualized, evidence-based strategy for Impella CP use in patients with AMICS.

• Study Hypothesis: Routine pre-PCI Impella CP will reduce the composite of all-cause death within 30 days after randomization or refractory shock within 48 hours after index PCI compared with revascularization first and selective post-PCI Impella CP.