The aim of this study is to evaluate the safety of ultra-low contrast coronary angiography in patients with pre-existing acute kidney injury.

The study is a non-inferiority open-label randomized controlled trial. Hospitalized patients who have AKI at admission or who develop AKI during admission and require invasive coronary angiography will be included in the trial. Once indication for invasive coronary angiography is determined, patients will be randomized to immediate angiography or to delayed angiography after renal function stabilizes. Immediate angiography will be performed within 24 of enrollment. Serum creatinine will be collected on enrollment, within 6 hours before coronary angiography, and at 24h, 48h and 1-week after the angiography, as expected in common practice. Pre- and post-hydration administration will be at the discretion of the treating physician. In case percutaneous coronary intervention is indicated it will be schedule for 7 days after angiography.

Definitions: AKI is defined as an increase in serum creatinine by ≥50% from baseline within 7 days or an increase in serum creatinine by ≥0.3 mg/dl within 2 days. CIN is defined as an increase in serum creatinine by 0.5mg/dl or a relative rise of 25% from the baseline value.

Inclusion Criteria:

• Hospitalized patients who have AKI at admission or who develop AKI during admission and require invasive coronary angiography will be included in the trial.

Exclusion Criteria:

• Stabilized renal function manifested by unchanged or downtrending serum creatinine during a 24-hour period prior to enrollment.
• Contraindication for invasive coronary angiography other than AKI.
• Percutaneous coronary intervention is indicated and cannot be postponed by 7 days.
• Need for renal replacement therapy before coronary angiography or planned renal replacement therapy after coronary angiography (if premeditated before coronary angiography).
• Administration of intravascular contrast media during 7 days prior to the coronary angiography or within 6 days after coronary angiography.
• Pregnant patients, prisoners, cognitively impaired subjects, age below 18 years, unable or unwilling to provide informed consent.