The Diagnostic and Prognostic Value of First Hour Glycogen Phosphorylase Isoenzyme BB Level in Acute Coronary Syndrome

Background: Evaluating patients with symptoms suggestive of acute coronary syndrome (ACS) is a time consuming, expensive and problematic process in the emergency department. This study aimed to evaluate the diagnostic and prognostic value of glycogen phosphorylase isoenzyme-BB (GP-BB) in ACS.

Methods: A total of 72 patients (mean age 61.8 ± 11.6 years) with ACS were enrolled. The ELISA method for determining GP-BB level was performed and considered positive at 〉 10 ng/mL. Duration of angina, type of ACS, demographic features, myoglobin, creatinine kinase and troponin T (cTnT) were also assessed. The cTnT levels eight hours after pain onset was considered the gold standard test for the diagnosis of myocardial infarction.

Results: The most sensitive biomarker at first hour of admission was GP-BB (95.8%). However, the specificity of GP-BB was low (43.7%). Receiver operating characteristics curve analysis of the GP-BB level for predicting myocardial infarction revealed the area under the curve value as 0.82 (SE 0.04; 95% CI 0.78-0.85). Positive treadmill exercise test (60% vs 17%, p = 0.047), coronary artery disease (CAD; 59% vs 19%, p = 0.007), percutaneous coronary intervention (44% vs 27%, p = 0.031) and 30-day mortality and/or readmission (33% vs 5%, p = 0.028) were found to be higher in unstable angina (UA) patients having GP-BB (+).

Conclusions: GP-BB is considerably cardiosensitive at the first hour of admission in patients with ACS, but the specificity of GP-BB is lower and it is elevated in nearly half of the patients with UA. However, in this group, GP-BB predicts significant CAD and the combined end-point of mortality and re-hospitalization.