ARI incidence was lower in the carvedilol plus NAC group compared with the metoprolol ( 21.0 % vs 42.1 % ; P = 0.002 ) or carvedilol ( 21.0 % vs 38.6 % ; P = 0.006 ) groups , but was similar between the metoprolol and carvedilol groups ( P = 0.62 ) .