Association between serum γ-glutamyltransferase levels and coronary microvascular function in hypertensive patients

Objective Serum γ-glutamyltransferase (GGT) level is an independent risk factor for cardiovascular (CV) disease, and there is a strong association between serum GGT levels and most CV risk factors, including hypertension; however, the role of serum GGT level as an independent risk factor for target organ damage in hypertension remains controversial. Accordingly, we aimed to determine whether serum GGT level is independently and specifically associated with coronary flow reserve (CFR) impairment in hypertensive patients. Methods We examined 100 never-treated and newly diagnosed hypertensive individuals, and CFR was achieved in 97 (97%) of them. They were divided into two groups based on serum GGT levels. Results Subjects with higher GGT had significantly impaired CFR as compared to those with lower GGT (2.10±0.36 versus 2.57±0.54, P<0.0001). After adjusting for potential confounders, including age, sex, body mass index, blood pressure, lipids and glucose, we found that serum GGT levels were independently associated with CFR impairment (β = -0.62, P<0.0001). We also found that GGT level was a good predictor of low CFR at the receiver-operating characteristic curve. Area under the curve was 79% [95% confidence interval: 0.70-0.88], and GGT level was significantly predictive of low CFR (P< 0.0001). Conclusion These results support a role for serum GGT level as an independent marker of target organ damage in hypertensive subjects without concomitant risk factors.