Prognostic value of serum gamma-glutamyl transferase activity after myocardial infarction

AIMS: Serum gamma-glutamyl transferase activity (gamma-GT) is able to catalyse low-density lipoprotein oxidation and has been detected in coronary atherosclerotic plaques. gamma-GT has been documented as an independent risk factor for cardiac mortality in middle-aged men. The purpose of this study is to determine the prognostic value of gamma-GT in patients with coronary artery disease. METHODS AND RESULTS: In a prospective study, gamma-GT and other cardiac risk factors were evaluated in 469 consecutive subjects with angiographically documented coronary artery disease, using mortality and mortality plus non-fatal myocardial infarction as end-points. gamma-GT showed an independent prognostic value beyond known established risk factors in the subgroup of 262 patients with previous myocardial infarction. At a 6-year follow-up, cardiac mortality was 25.2% in patients with gamma-GT >40 U x l(-1)vs 13.9% in those with gamma-GT <40 U x l(-1)(P=0.038). When both cardiac mortality and non-fatal myocardial infarction were considered as end-points, these events were recorded in 32.7% of patients with gamma-GT >40 U x l(-1)and in 20.4% of those with levels <40 U x l(-1)(P=0.031). Excess mortality and non-fatal infarction in patients with high gamma-GT levels were concentrated in the first 2 years of follow-up (P=0.014). The association of gamma-GT values >40 U x l(-1), previous myocardial infarction, and multiple vessel disease identified a subgroup of 168 patients with the highest risk of cardiac events at 6 years (P=0.024). The relationship between gamma-GT levels and cardiac events remained significant after adjustment for cardiac risk factors, and possible confounders, including alcohol consumption. gamma-GT did not show significant prognostic value in the 207 patients without previous myocardial infarction. CONCLUSION: gamma-GT is an independent cardiac risk factor in ischaemic patients with established coronary atherosclerosis and previous myocardial infarction.