Dosing of iodinated contrast volume: a new simple algorithm to stratify the risk of contrast-induced nephropathy in patients with acute coronary syndrome.

OBJECTIVES AND
BACKGROUND: Previous studies on contrast-induced nephropathy (CIN) have identified contrast volume (CV) as a risk factor. The aim of our research was to define the safe dose of contrast media based on absolute CV, maximum allowable contrast dose (MACD) and estimated glomerular filtrate rate (eGFR). METHODS AND
RESULTS: A total of 940 consecutive patients with acute coronary syndrome (ACS) were enrolled. Fifty-four patients developed CIN. MACD was defined as 5*body weight/serum creatinine. When using a CV higher than MACD, CIN-risk was increased 19-fold (OR 9.810-39.307, P < 0.001). For the CV/eGFR ratio, we found that for every increase of one-tenth, CIN-risk increased by 4.9% (OR 1.037-1.061, P < 0.001). The discriminative ability of CV (C statistic = 0.626 ± 0.038) was significantly lower than for the CV/MACD (C statistic = 0.782 ± 0.036, P = 0.003) and CV/eGFR (C statistics: 0.796 ± 0.033 for MDRD-4, 0.796 ± 0.034 for Cockcroft-Gault, and 0.803 ± 0.033 for CKD-EPI; P < 0.001). There were no differences in the discriminative ability to predict CIN between the three eGFR equations. The combination of CV/MACD and CV/eGFR in a single protocol increases the positive predictive value of the Mehran risk score (40.7% vs. 8.8%) with the same sensitivity (90.7% vs. 83.3%). High doses of relative CV (CV/MACD and CV/eGFR) were also significantly associated with higher in-hospital mortality, reinfarction, and heart failure.
CONCLUSIONS: A sequential protocol based on CV/MACD and CV/eGFR appropriately identified those ACS patients who developed CIN, with predictive values similar to a Mehran score, reducing the false positive rate. It is also useful to predict risk of in-hospital cardiac events regardless of GRACE score.