Immunoenzymometric Assay of Human Glycogen Phosphorylase Isoenzyme BB in Diagnosis of Ischemic Myocardial Injury

With a new immunoenzymometric assay we measured human glycogen phosphorylase isoenzyme BB (GPBB) in 116 healthy individuals, 14 patients with stable angina, 107 nontraumatic chest pain patients on admission to the emergency department [45 acute myocardial infarction (AMI), 49 unstable angina, 13 other diseases], and in serial samples from 41 AMI patients. GPBB was com-pared with creatine kinase (CK), CKMB mass, myoglobin, and cardiac troponin T. Receiver-operating characteristic plots demonstrated the significantly greater (P O.012) discriminatory power of GPBB to detect acute ischemic coronary syndromes compared with all other tested markers. GPBB was the most sensitive marker for detec-tion of AMI during the first 4 h after onset of chest pain, and only GPBB was increased above the upper reference limit (7 g/L) on admission in patients who had unstable angina at rest and reversible ST-T alterations. This and the high early sensitivity of GPBB are most likely ex-plained by its function as a key enzyme of glycogenoly-sis. Indexing Terms: myocardial infarction/unstable angina pecto-ris/creatine kinase/myoglobin/troponin T Early identification and confirmation of acute myo-cardial infarction (AMI) is essential for correct patient care and disposition decisions (1)5 Because as many as one-fourth of AMI patients present with atypical signs and symptoms (1, 2),-5 % of patients with AMI are released unintentionally from the emergency depart-ment, which places them at greater risk of morbidity and mortality resulting from complications (2). Al-though electrocardiography (ECG) is considered th