The addition of intravenous (IV) N-acetylcysteine (NAC) to IV glyceryl trinitrate (GTN) significantly reduced infarct size by approximately one third in patients undergoing percutaneous coronary intervention (PCI) after ST-segment elevation acute myocardial infarction (STEMI), according to results from the NACIAM Trial presented Aug. 28 during ESC Congress 2016 in Rome.

The placebo-controlled, double-blind trial, included 112 STEMI patients (mean age 64 years) from three Australian hospitals. All patients underwent emergency PCI and also received low dose intravenous GTN. Prior to PCI patients were randomized to receive either high dose (15 grams/24 hours) NAC or an identical placebo, both delivered intravenously over 48 hours. Cardiac magnetic resonance (CMR) imaging was performed within one week and again three months post MI.

Overall findings found that patients who received NAC had reductions in infarct size of 33 percent and 50 percent, respectively, compared to placebo (p=0.02 for both). Additionally, there was a similar but not significant trend towards reduction in creatine kinase release.

Researchers also noted that myocardial salvage, measured at one week, was roughly doubled in patients who received NAC (60 percent vs. 27 percent, p<0.001), and there was also evidence of accelerated tissue reperfusion and hypochlorous acid “scavenging” in these patients. The combination of cardiac readmissions and deaths was less frequent in NAC-treated patients (three vs. 16 patients) over the follow-up period of approximately two years. Safety endpoints including hypotension, bleeding and contrast-induced nephropathy were similar in both groups.

“Intravenous NAC administration was associated with more rapid chest pain resolution, improved myocardial salvage, a favourable in-hospital safety profile, sustained infarct size reduction at three months post-STEMI, and promising clinical outcomes at two years,” concludes Sivabaskari Pasupathy, PhD candidate, from the University of Adelaide, in Australia. “While the results of this study are encouraging, we would prefer to regard NACIAM as the precursor of a follow-up study, sized for clinical end-points.”

"Due to the very small sample size, the confidence limits around the primary endpoint are quite large. Therefore this study requires validation in a much larger study before we would begin to adopt this strategy in practice," said Kim A. Eagle, MD, MACC, editor in chief of ACC.org.

Keywords: ESC Congress, Acetylcysteine, Myocardial Infarction, Nitroglycerin, Percutaneous Coronary Intervention

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