NEW YORK (Reuters Health) – A study from Japan finds that sodium bicarbonate plus sodium chloride is more effective than sodium chloride alone for the prevention of contrast-induced nephropathy (CIN) in patients with moderate kidney dysfunction who need coronary angiography.

The combination had both short and long term benefits, Dr. Masayuki Motohiro from Kyoto Kujo Hospital in Kyoto and colleagues found in a prospective, randomized, 2-center study, published March 21 in the American Journal of Cardiology.

Sodium bicarbonate plus sodium chloride decreased the incidence of CIN relative to sodium chloride alone and was also associated with improved renal function at 30 days.

The study included 155 patients an estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 m2 who were undergoing planned coronary angiography; 78 were randomly assigned to sodium bicarbonate plus sodium chloride (the bicarbonate group) and 77 to sodium chloride alone (the chloride group).

All patients received 0.9% sodium chloride at 1 ml/kg/hour for 12 hours before and 12 hours after the procedure. Sodium bicarbonate (154 mEq/L in 5% dextrose) was infused at 1 ml/kg/hour 3 hours before the procedure and 6 hours after the procedure.

Baseline eGFR was not significantly different in the bicarbonate and chloride group (45.7 and 42.3 ml/min/1.73 m2, respectively). Patients in the bicarbonate group had a higher eGFR than those in the chloride group on day 2 (45.8 vs 40.9 ml/min/1.73 m2; P = 0.031) and at 1 month (49.5 vs 43.7 ml/min/1.73 m2; P = 0.019).

Mean serum creatinine levels were also similar at baseline in the two groups (around 1.55 mg/dL). On day 1 and at 1 month after contrast administration, a significant decrease in mean serum creatinine was noted in the bicarbonate group (1.49 and 1.46 mg/dL, respectively). In the chloride group, in contrast, an increase in serum creatinine was noted on day 1 and at 1 month (1.57 and 1.60 mg/dL, respectively).

CIN occurred in a total of 12 patients (7.7%). There were 2 cases in the bicarbonate group (2.6%) compared with 10 in the chloride group (13.0%), yielding a relative risk of 0.176.

The average contrast dose administered was significantly higher in patients who developed CIN relative to those who did not (171 vs 132 mL; P < 0.01). Ten of the 12 patients who developed CIN had diabetes. The protective effect of sodium bicarbonate against CIN in this study was “impressive,” Dr. Motohiro and colleagues say, “and no significant side effects were observed in any patient.” Limitations of the study, the researchers say, include its small sample size and short follow up (1 month). The effect of sodium bicarbonate on more long-term outcomes in patients with abnormal renal function remains unknown, they note. Furthermore, they say it “could be argued” that the dose of sodium bicarbonate used in the study was higher than needed to prevent CIN. “A substantially lower intravenous dose may have been equally effective and this question merits further study,” they say. Am J Cardiol