Primary endpoint: Decrease in glomerular filtration rate (GFR) within 48 hours. GFR is calculated using the abbreviated Modification of Diet in Renal Disease Study equation. Secondary endpoints: Development of contrast nephropathy defined by increase in serum creatinine concentration of at least 44umol/l within 48 hours, an increase >=25% in the baseline serum creatinine concentration within 48 hours, or defined as an increase >=25% in the baseline serum cystatin C concentration or an increase >=0.35mg/l in serum cystatin C concentration within 48 hours; increase in serum cystatin C level at day 1 and 2, in-hospital morbidity (nonfatal myocardial infarction) and mortality, dialysis, length of stay, total costs of hospitalization, 3-/12-month mortality, 3-/12-month hospitalization for cardiac causes, and GFR at 3 and 12 months.