Elevated gamma-glutamyl transferase levels are associated with stroke recurrence after acute ischemic stroke or transient ischemic attack

Aims Gamma-glutamyl transferase (GGT) is considered a marker of oxidative stress in vivo. In this study, we aimed to examine the association of serum GGT levels with 3-month and 1-year stroke recurrence in patients with acute ischemic stroke or transient ischemic attack (TIA). Methods We conducted a large and multicenter cohort study. Participants with ischemic stroke or TIA who had a baseline GGT measurement were enrolled in the China National Stroke Registry-3 study from August 2015 to March 2018. They were divided into four groups according to sex-specific quartiles of GGT levels. The effect of GGT on stroke recurrence and other vascular events was examined during the 1-year follow-up period. Multivariate Cox regression models were performed to evaluate the association. Discrimination tests were used to examine the degree to which incorporating GGT into the conventional model predicted stroke adverse outcomes. Results A total of 12,504 patients were enrolled. At both the 3-month and 1-year follow-ups, patients in the highest quartile group of GGT levels exhibited a higher risk of stroke recurrence [HR 1.32 (95% CI 1.07-1.63), HR 1.34 (95% CI 1.13-1.60)], ischemic stroke [HR 1.37 (95% CI 1.10-1.71), HR 1.37 (95% CI 1.14-1.64)], and combined vascular events [HR 1.34 (95% CI 1.09-1.65), HR 1.34 (95% CI 1.13-1.59)] than those in the lowest quartile group. Moreover, the Kaplan-Meier curves revealed that the incidence rates of stroke adverse outcomes were quite different in the four groups. The highest quartile group showed the highest cumulative incidence, while the lowest quartile group showed the lowest cumulative incidence. After applying discrimination tests, adding GGT into the conventional model resulted in slight improvements in predicting stroke adverse outcomes (NRI: 10%-14%). Conclusion This study demonstrated that elevated GGT levels were positively associated with an increased risk of stroke adverse outcomes, namely, recurrence, ischemic stroke, and combined vascular events.