Peak serum TnI concentration was similar in the intervention and usual care groups ( median [ interquartile range ] : 10.0 [ 5.3-21 .5 ] vs 7.8 [ 5.0-21 .8 ] ng litre ( -1 ) ; P = 0.85 ) , and no differences were observed in serum TnI concentrations over 72 h ( repeated-measures anova , P = 0.51 ) .