Prevention of contrast-induced nephropathy in vascular patients undergoing angiography: a randomized controlled trial of intravenous N-acetylcysteine.

OBJECTIVE(S): Apart from proper hydration, only oral N-acetylcysteine (NAC) has shown efficacy in reducing radiographic contrast media (RCM)-induced acute renal failure, though its benefit has been challenged. We investigated the effect of intravenous (i.v.) NAC on renal function in patients with vascular disease receiving RCM for angiography.

METHODS

Single-center, randomized, double-blind, placebo-controlled trial. Based on a previous study, a trial with 44 patients each in placebo and treatment arms would give at least 80% power to show a statistically significant difference at the 5% level. Vascular patients undergoing angiography were consented and segregated into those whose serum creatinine (SC) level was normal or raised (men >1.32 mg/dl; women >1.07 mg/dL). All patients received 500 mL i.v. normal saline 6 to 12 hours prior to and then after angiography. Groups with normal SC and raised SC were randomly assigned to either 1 g of NAC with normal saline before and after angiography or nothing (placebo). Main outcome measures were change in SC and creatinine clearance (CrCl) as measured 1, 2, and 7 days postangiography (with comparison between active and placebo groups using unpaired t test) and incidence of acute renal decline (>25% or 0.5 mg/dL rise in SC) at 48 hours (with comparison between active and placebo using the Fisher exact test).

RESULTS

Forty-six patients received NAC (29 normal SC, 17 raised SC), and 48 received placebo (27 normal SC, 21 raised SC). There was no significant difference in postangiography SC or CrCl at any of the time points measured between NAC and placebo in patients with either normal or raised SC. In the raised SC group, 3 patients from both the NAC and placebo groups suffered acute renal declines. Importantly, at 48 hours, the impaired SC group had a significant reduction in CrCl (-14% +/- 41% vs +18% +/- 58%: P = .0142) and a significant rise in SC (+7.0 +/- 25% vs -1.6% +/- 10%; P = .0246) when compared with the normal SC group.

CONCLUSIONS

NAC (i.v. at 1 g) precontrast and postcontrast does not confer any benefit in preventing RCM-induced nephropathy in vascular patients. Patients with pre-existing raised SC have an increased risk of renal impairment as defined by a fall in CrCl and a rise in SC post-RCM when compared with patients with normal SC who appear to benefit from hydration.