ABSTRACT
BACKGROUND: A perioperative myocardial infarction(PMI) is one of the major complications after CABG. Among diagnostic methods of PMI, CK-MB activity assays have been increasingly replaced by CK-MB mass assays, which have more sensitive, simple measurement. Also, new cardiac-specific and -sensitive marker, cardiac troponin I(cTnI), has been shown to be a marker of myocardial infarction. We report our evaluation of clinical significance of CK-MB mass and cTnI as a marker of PMI after CABG. MATERIAL AND METHOD: We studied 32 patients who underwent CABG at Kangdong Sacred Hospital between April 2000 and April 2001. Postoperative serum CK-MB activity level, serum CK-MB mass, cTnI, electrocardiogram, echocardiogram, and clinical data were recorded prospectively. The diagnosis of PMI was defined as positive 2 among 3 or all of the following ; by a new Q wave on the electrocardiogram, by serum CK-MB activity higher than 200 IU/L within 72 hours after operation, and by new regional wall motion abnormality on the echocardiogram. RESULT: After CABG, 3 patients had sustained a PMI according to current diagnostic criteria. As serum CK-MB activity time course, a level of CK-MB activity 12 hours after CABG had very linear correlated significance with serum CK-MB mass 24 hours(R=0.946) and cTnI 48 hours(R=0.933) after CABG(p=0.000). As we used a receiver operating characteristics curve(ROC curve) for a diagnostic cutoff value in patients with PMI, serum CK-MB mass levels higher than 30.05 ug/L 24 hours after CABG detected the presence of PMI with an area under the ROC curve of 1.0, a sensitivity of 100%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 100%. Also serum cTnI levels higher than 17.15 ug/L 48 hours after CABG detected the presence of PMI with an area under the ROC curve of 0.98, a sensitivity of 100%, a specificity of 96.6%, a positive predictive value of 75%, and a negative predictive value of 100%. CONCLUSION: We concluded that both the measurement of CK-MB mass and cTnI are the easier, accurate methods as a diagnostic marker of PMI after CABG, also as a proposal of diagnostic cutoff value enables to an early detection of PMI. However, a larger number of patient will be needed because of statistic limitation that a small number of participating patients, a small number of PMI.