Drinking water may shield kidneys during emergency heart procedures

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Inclusion Criteria All of the following must be present: * Age ≥18 years at the time of randomization * Clinical diagnosis of STEMI, confirmed by 12-lead ECG showing ≥30 minutes of ST-segment elevation ≥1 mm in ≥2 contiguous limb leads or ≥2 mm in ≥2 contiguous precordial leads, or new left bundle branch block with a clinical presentation consistent with acute myocardial infarction * Decision to proceed with primary PCI as the reperfusion strategy, within 12 hours of symptom onset (or up to 24 hours if evidence of persistent ischaemia or haemodynamic instability) * Estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73m², calculated by the CKD-EPI 2021 formula from the most recent available serum creatinine measurement prior to contrast exposure * Ability to swallow and safely tolerate oral fluids, as assessed by the attending physician * Oral informed consent obtained from the patient or a legally authorized representative (deferred consent protocol applies in emergencies per IRB approval) Exclusion Criteria: * \- Cardiogenic shock on presentation, defined as systolic blood pressure \<90 mmHg for \>30 minutes despite fluid resuscitation, or requirement for vasopressor or inotropic therapy to maintain SBP ≥90 mmHg, with evidence of end-organ hypoperfusion (Killip Class IV) * Acute pulmonary oedema or Killip Class III with SpO₂ \<90% on room air, bilateral crepitations \>50% of lung fields, or chest X-ray showing pulmonary venous congestion requiring urgent diuresis * Pre-existing dialysis dependence (haemodialysis or peritoneal dialysis) or eGFR \<30 mL/min/1.73m² on admission * Active vomiting, dysphagia, altered consciousness (GCS \<14), or any clinical condition precluding safe oral fluid intake, as assessed by the attending physician * Administration of any IV hydration protocol for CIN prevention prior to randomization (patients may have received standard IV fluids for other indications; these are documented but do not constitute exclusion unless specifically intended as CIN prophylaxis) * Known severe allergy to iodinated contrast media that cannot be managed with pre-medication (moderate/mild allergies and prior mild reactions are not exclusions) * Concurrent administration of known nephrotoxic agents within 48 hours that cannot be withheld or dose-adjusted: aminoglycoside antibiotics (gentamicin, amikacin), high-dose loop diuretics in the context of diuretic nephropathy, or cisplatin-based chemotherapy * Pregnancy (confirmed by urine or serum beta-hCG) or active breastfeeding * Estimated life expectancy \<30 days from a non-cardiac cause (advanced malignancy, end-stage liver disease, multiorgan failure)