With the “Universal Definition,” Measurement of Creatine Kinase-Myocardial Band Rather Than Troponin Allows More Accurate Diagnosis of Periprocedural Necrosis and Infarction After Coronary Intervention
What is the best biomarker for defining post-percutaneous coronary intervention (PCI) myocardial infarction (MI)?
The authors evaluated 32 patients who underwent multivessel PCI and cardiac magnetic resonance (CMR) imaging to assess periprocedural MI. All patients had cardiac troponin I, creatine kinase-myocardial band (CK-MB), and inflammatory markers measured at baseline, 1 hour, 6 hours, 12 hours, and 24 hours after the procedure. Patients were divided into three groups based on post-procedural markers of myonecrosis: group 1 (no injury with biomarker <99th percentile), group 2 (periprocedural myonecrosis with biomarker 1-3 x upper limit of normal [ULN]), and group 3 (post-PCI MI (>3 x 99th percentile). Differences in inflammatory profiles and injury detected on CMR as late gadolinium enhancement (LGE) were analyzed.
Troponin elevation was common, and 26 patients were defined as post-PCI MI based on the troponin level, but only a small minority had evidence of an abnormality on CMR-LGE. With CK-MB, there were 17, 10, and 5 patients in groups 1-3, respectively. Patients with CK-MB–defined post-PCI MI were more likely to demonstrate with new CMR-LGE injury. The receiver operating curve analysis for detection of CMR-LGE showed areas under the curve of 0.985 for cardiac troponin I versus 0.970 for CK-MB, with no significant difference between the two areas. While there was no difference in the choice of using cardiac troponin I versus CK-MB, the current cutoff of 3 x ULN had poor specificity for troponin (specificity = 22%) compared with CK-MB (specificity = 92%). Based on this study, the optimal troponin cutoff for defining post-PCI myonecrosis would be a troponin of >40 x ULN.
Compared with a troponin level >3 x ULN, an elevation in CK-MB >3 x ULN is a more sensitive marker of post-PCI MI.
The universal definition of MI supports preferential use of troponin 3 x ULN as the definition of periprocedural MI, although this cutoff is arbitrary. This study, although small, suggests that the old CK-MB–based standard is remarkably superior to the universal definition. Studies evaluating post-PCI MI should continue to use a CK-MB–based definition until larger studies can define the optimal troponin cutoff for defining post-PCI MI.
Clinical Topics: Invasive Cardiovascular Angiography and Intervention
Keywords: Myocardial Infarction, Infarction, Biological Markers, Troponin I, Creatine, Sensitivity and Specificity, Creatine Kinase, MB Form, Necrosis, Magnetic Resonance Spectroscopy, Troponin, Percutaneous Coronary Intervention
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