the hypothesis is that elevation of the intrarenal resistive index (RI) characterizes patients at elevated risk for subsequent CA-AKI and integrates items of the Mehran AKI risk score into a single, readily obtainable parameter. Impella-mediated nephroprotection confers to reduction of elevated RI by restoration of intrarenal venous flow profile.

Contrast-associated acute kidney injury (CA-AKI) occurs in up to 10% of patients undergoing percutaneous coronary intervention (PCI) for coronary revascularization. CA-AKI is associated with impaired long-term outcome. This causes so-called "Renalism", describing the fact that patients with chronic kidney disease (CKD) in need of live-saving revascularizations are not offered PCI procedures in the risk of imminent CA-AKI.

Retrospective studies and one-single-center pilot study described protective effects of Impella-protected PCI to reduce the incidence of CA-AKI. However, mechanisms involved of nephroprotection by Impella remain obscure. Deciphering these, is a prerequisite to tailor nephroprotection to the patients in need and to gain a label for nephroprotection by Impella.

Inclusion Criteria:

Subjects must meet all of the Inclusion Criteria to participate in the trial.

1. Age ≥18 years and <90 years
2. Scheduled for PCI or PROTECTED PCI in near future (1 week) or PCI same day.

Exclusion Criteria:

Subjects must NOT meet any of the following Exclusion Criteria to participate in the trial.

1. Severe chronic kidney disease with eGFR ≤ 20 ml/min or on dialysis
2. Patients with AKI within the last seven days prior screening or incipient AKI (in cases, where AKI cannot be ruled out as a cause for elevated serum creatinine, a rise or fall above 30% of a second serum creatinine measurement obtained within 12 to 24 hours is regarded indicative of AKI).
3. STEMI ≤24 hours from the onset of ischemic symptoms or at any time if mechanical complications of transmural infarction are present (e.g., VSD, papillary muscle rupture, etc.)
4. Cardiogenic shock (SBP <80 mmHg for ≥30 mins and not responsive to intravenous fluids or hemodynamic deterioration for any duration requiring pressors or mechanical circulatory support, including IABP)
5. Cardiorespiratory arrest related to the current admission unless subject is extubated for >24 hours with full neurologic recovery and hemodynamically stable.
6. Platelet count <75,000 cells/mm3, bleeding diathesis or active bleeding, coagulopathy or unwilling to receive blood transfusions.
7. Pregnant or child-bearing potential unless negative pregnancy test within 1 week
8. Participation in the active treatment or follow-up phase of another clinical study of an investigational drug or device that has not reached its primary endpoint
9. Any medical or psychiatric condition such as dementia, alcoholism or substance abuse which may preclude informed consent or interfere with any of the study procedures, including follow-up visits
10. Any non-cardiac condition with life expectancy <1 years (e.g., cirrhosis, cancer not in remission, etc.)
11. Subject belongs to a vulnerable population (defined as individuals with mental disability, persons in nursing homes, impoverished persons, homeless persons, nomads, refugees and those permanently incapable of giving informed consent; vulnerable populations also may include members of a group with a hierarchical structure such as university students, subordinate hospital and laboratory personnel, employees of the Sponsor, members of the armed forces and persons kept in detention)

Patients with indication for PCI or Impella-protected PCI