Clinical and angiographic correlates of normal creatine kinase with increased MB isoenzymes in possible acute myocardial infarction

A retrospective study of patients with possible acute myocardial infarction was conducted over a 2-year period to evaluate the clinical characteristics, angiographic findings, and in-hospital prognosis in patients with normal total creatine kinase (CK) activity and increased MB isoenzyme activity (CK4MB). Thirty-nine cases were identified (study group) and compared with cases of Q-wave (n = 77) and non—Q-wave (n = 60) infarctions. Compared with the Q-wave group, study group patients were older (67.5 ± 9.0 vs 60.8 ± 11.5 years; p < 0.01) and more often had previous diagnoses of coronary disease (52.6% vs 18.2%; p < 0.01) and peripheral vascular disease (28.9% vs 10.4%; p = 0.02). Angina (92.2% vs 65.8%; p < 0.01) and ST elevation (81.8% vs 13.2%; p < 0.01) were more common in the Q-wave group. Nearly identical clinical profiles and electrocardiographic findings were observed in the study and non—Q-wave groups. Angiographic analysis revealed a higher frequency of multivessel disease in the study group (89.6%) than in the Q-wave group (48.6%, p < 0.01) but no difference between the study group and the non—Q-wave group (79.6%; p not statistically significant). Left ventricular function and inhospital complications were similar among groups. It is concluded that patients with normal total CK activity and increased CK-MB concentration represent a subgroup of patients with non—Q-wave infarction with a high prevalence of multivessel coronary disease.