Effects of Gamma-Glutamyl Transferase on Stroke Occurrence Mediated by Atrial Fibrillation

BACKGROUND AND PURPOSE: Gamma-glutamyl transferase (GGT) is reported to be associated with stroke independently of the conventional risk factors. However, the underlying mechanism remains to be identified. This study focused on atrial fibrillation (AF), which also reportedly has a close association with GGT. METHODS: Acute ischemic stroke patients who were admitted to the Seoul National University Hospital within 7 days of stroke onset were analyzed. Multinomial logistic regression was performed to assess the relationship between GGT and cardioembolic stroke. Mediation analysis based on binary logistic regression was used to determine whether AF mediates the relationship between GGT and cardioembolic stroke. RESULTS: AF was found in 132 (15.0%) of 880 eligible patients with acute ischemic stroke, and 270 (30.7%) patients were categorized as cardioembolic stroke. High GGT levels in acute ischemic stroke patients was associated with cardioembolic stroke [odds ratio (OR)=3.42, 95% CI=1.59–7.37], but not with large-artery atherosclerosis stroke (OR=1.10, 95% CI=0.54–2.23). Approximately half (53.9%) of the total effect of GGT levels on cardioembolic stroke was mediated by AF. CONCLUSIONS: The GGT level was significantly associated with cardioembolic stroke via AF. The results obtained in the present study may explain why GGT is associated with stroke.