tokens: Multivariable Cox regression analysis revealed a non - linear association across the three groups for mortality ( HR [ CI ] ; < 24 h : 1.0 , reference ; 24 - 48 h : 0.73 [ 0.27 - 1.86 ] ; > 48 h : 2.25 [ 1.22 - 4.15 ] ) after adjustments for age , sex , Killip classification , percutaneous coronary intervention , blood pressure , creatinine , peak creatine kinase myocardial band fraction , left ventricular ejection fraction , and type of rupture .