Utility of cardiac biomarkers in predicting infarct size, left ventricular function, and clinical outcome after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

OBJECTIVES

We sought to determine the best cardiac biomarker to predict infarct size, left ventricular ejection fraction (LVEF), and clinical outcome in patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

The cardiac biomarkers, creatine kinase (CK), CK-MB, and troponins T and I are routinely measured after myocardial infarction. However, their correlation with functional and clinical outcomes after PCI for STEMI is not well established.

METHODS

In the EVOLVE (EValuation Of MCC-135 for Left VEntricular Salvage in Acute Myocardial Infarction) trial, patients were randomized to receive intracellular calcium modulator as adjunct to primary PCI for first large STEMI. Cardiac biomarker levels were determined in 378 patients before PCI and serially up to 72 h. Single-photon emission computed tomography was performed after 5 and 30 days, and patients were monitored up to 180 days.

RESULTS

All single time-point, peak, and area under time-concentration curve of CK, CK-MB, and troponins T and I after PCI significantly correlated with infarct size and LVEF. In particular, 72-h troponin I (TnI72h) correlated strongly with 5-day and 30-day infarct size (r > 0.70; p < 0.001). A TnI72h threshold >55 ng/ml was 90% sensitive for large infarct size (> or =10%) and low LVEF (< or =40%) with specificities of 70% and 52%, respectively (c = 0.88, 0.81; p < 0.001). The highest TnI72h tertile was associated with increased 180-day composite clinical events (23% vs. 23% vs. 42%; p = 0.001) and independently predicted adverse events (hazard ratio = 2.3; p = 0.01).

CONCLUSIONS

Assessing TnI72h after primary PCI is a simple, effective method to estimate infarct size, LVEF, and potentially useful for risk stratification.