The contemporary value of peak creatine kinase-MB after ST-segment elevation myocardial infarction above other clinical and angiographic characteristics in predicting infarct size, left ventricular ejection fraction, and mortality

BACKGROUND: Complex multimarker approaches to predict outcome after ST-elevation myocardial infarction (STEMI) have only considered a single baseline sample, while neglecting easily obtainable peak creatine kinase and creatine kinase-MB (CK-MB) values during hospitalization.

METHODS: We studied 476 patients undergoing primary percutaneous coronary intervention for STEMI and cardiac magnetic resonance imaging (CMRI) at 4-6 months after STEMI. We determined the association with cardiac biomarkers (peak CK-MB, peak troponin T, N-terminal pro-brain natriuretic peptide), clinical and angiographic characteristics with infarct size, and LVEF, followed by association with mortality in 1120 STEMI patients.

RESULTS: Peak CK-MB was the strongest predictor for infarct size (P<0.001, R 2 =0.60) and LVEF (P<0.001, R 2 =0.40). The additional value of clinical and angiographic characteristics was limited. The optimal peak CK-MB cutpoints, for differentiation among small (<10% of the left ventricle), moderate (≥10%-<30%), and large infarct size (≥30%), were 210 U/L and 380 U/L, respectively. These cutpoints were associated with 90-day mortality; the hazard ratio for moderate infarct was 2.99 (95% confidence interval [CI]: 1.51-5.93, P=0.002) and for large infarct 6.53 (95% CI: 3.63-11.76, P<0.001).

CONCLUSIONS: Classical peak CK-MB measured during hospitalization for STEMI was superior to other clinical and angiographic characteristics in predicting CMRI-defined infarct size and LVEF, and should be included and validated in future multimarker studies. Peak CK-MB cutpoints differentiated among infarct size categories and were associated with increased 90-day mortality risk.