Glycogen phosphorylase isoenzyme BB in early diagnosis of acute coronary syndrome

Abstract

Objective: To investigate the usefulness and diagnostic performance of glycogen phosphorylase BB (GPBB) to aid early diagnosis of acute coronary syndrome and to compare with cardiac-specific troponin I (cTnI), creatine kinase isoenzyme MB and myoglobin. Material and Method: Non-traumatized 72 patients arriving at the emergency department within 3 hours after the onset of chest pain suggestive of acute coronary syndrome were included. The patients were classified as having acute myocardial infarction (AMI) or unstable angina pectoris (UAP). Blood samples were obtained on arrival (0 hours), 6 hours, and 24 hours. To determine the diagnostic performances of GPBB and other cardiac markers for ACS, sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios and receiver operating characteristic (ROC) curves with areas under curves were calculated. Results: Seventy two non-traumatic chest pain patients and 45 controls were enrolled. GPBB was the most sensitive biochemical cardiac marker of all tested in AMI and UAP patients on admission, whereas its specificity was low In both AMI and UAP patients, the area under the GPBB ROC curve, was significantly greater than the areas under all other ROC curves on admission. Conclusion: GPBB is a promising enzyme for the early laboratory detection of ischemic myocardial damage. Because the diagnostic specificity of GPBB for myocardial damage is low, a positive GPBB result should subsequently be confirmed by cTnI measurement. However; further studies on specificity and development of a fast, automated assay are necessary before GPBB can be recommended as a routine diagnostic tool.