ORIGINAL PAPER Impact of N-acetylcysteine on contrast-induced nephropathy defined by cystatin C in patients with ST-elevation myocardial infarction undergoing primary angioplasty Michal Droppa • Steffen Desch • Patrick Blase • Ingo Eitel • Georg Fuernau • Gerhard Schuler • Volker Adams • Holger Thiele Received: 11 January 2011 / Accepted: 20 June 2011 / Published online: 28 June 2011 Ó Springer-Verlag 2011 Abstract Background The aim of this study was to assess the effects of N-acetylcysteine (N-ACC) on contrast-induced nephropathy (CIN) defined by Cystatin C (Cys-C) serum levels and to evaluate the influence of Cys-C on clinical outcome in patients with ST-elevation myocardial infarc- tion (STEMI). Methods In total, 251 patients with STEMI undergoing primary percutaneous coronary intervention (PCI) were randomized to either high-dose N-ACC (2 9 1200 mg/d for 48 h) with optimal hydration or placebo plus optimal hydration. Serum Cys-C was measured at baseline, immediately, 24, 48 and 72 h after PCI. CIN was defined as an increase in serum Cys-C levels of 25% or more from baseline within 72 h after PCI. Major adverse cardiac events (MACE)—defined as death, recurrent infarction and congestive heart failure—within 6 months were recorded. Results Baseline Cys-C was 1294 ± 611 and 1352 ± 811 ng/mL (p = 0.54) for the N-ACC and placebo group, respectively. There was a steady increase in Cys-C in both groups within the first 72 h after randomization. CIN occurred in 74.6 and in 70.4% of patients in the N-ACC and placebo group, respectively (p = 0.46). The magnitude of increase in the serum concentration of Cys-C was an independent predictor for MACE after 6 months of follow-up. Conclusions High-dose N-ACC does not provide addi- tional benefit over placebo with respect to Cys-C defined CIN in STEMI patients undergoing primary PCI. The magnitude of increase in Cys-C serum levels in the early course after STEMI is a predictor of medium-term MACE. Keywords Cystatin C Á Infarction Á Nephropathy Á Contrast media Á Reperfusion Introduction Contrast-induced nephropathy (CIN) is a common com- plication of percutaneous coronary intervention (PCI) and is associated with prolonged hospitalization and adverse clinical outcome [1–3]. Patients with acute ST-elevation myocardial infarction (STEMI) are at high risk because of frequent hemodynamic instability and the lack of hydration before contrast administration [4]. High-dose N-acetylcysteine (N-ACC) might be effective in pre- venting CIN as defined by an increase in creatinine serum levels, although previous studies showed inconsistent results [5–13]. Cystatin C (Cys-C) is a small 13 kDa basic protein which is produced in all nucleated cells at a constant rate. Renal elimination is solely due to glomerular filtration. Plasma concentration of Cys-C is only marginally influ- enced by factors like age, sex and muscle mass [14]. Cys-C is, therefore, considered a superior marker for glomerular filtration rate (GFR) and more sensitive for renal injury in comparison to creatinine [15–18]. As a result, Cys-C may also predict declining kidney function even when the GFR is actually near normal range [19]. M. Droppa and S. Desch contributed equally to this manuscript. Senior authors, V. Adams and H. Thiele, contributed equally to this manuscript. http://www.ClinicalTrials.gov: NCT00463749 M. Droppa Á S. Desch Á P. Blase Á I. Eitel Á G. Fuernau Á G. Schuler Á V. Adams Á H. Thiele (&) Department of Internal Medicine/Cardiology, University of Leipzig, Heart Center, Stru ¨mpellstr. 39, 04289 Leipzig, Germany e-mail: thielh@medizin.uni-leipzig.de 123 Clin Res Cardiol (2011) 100:1037–1043 DOI 10.1007/s00392-011-0338-8