Ying Shen, Feng Hua Ding, Feng Wu, Zhen Sun, Rui Yan Zhang, Qi Zhang, Lin Lu, Zong Gui Wu and Wei Feng Shen
Objective: Renal dysfunction represents a risk factor for poor coronary collateral growth. We investigated whether Glomerular Filtration Rate (GFR) estimated with the cystatin C-based formula (GFRCYS) is superior to that with the creatinine-based abbreviated Modification of Diet in Renal Disease (GFRMDRD) and the Chronic Kidney Disease Epidemiology Collaboration (GFREPI) equations for evaluating coronary collateralization in type 2 diabetic patients with stable coronary artery disease. Methods: GFR was estimated with creatinine- and cystatin C- based equations in 302 diabetic and 127 nondiabetic patients with stable angina and angiographic total occlusion of at least one major coronary artery. The degree of collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded as poor (Rentrop score of 0 or 1) or good collateralization (Rentrop score of 2 or 3). Results: In diabetic patients, GFRCYS correlated more closely with Rentrop score than GFRMDRD (Spearmen’s r=0.44 vs. Spearmen’s r=0.30, P=0.047) and GFREPI (Spearmen’s r=0.44 vs. Spearmen’s r=0.29, P=0.028), and area under the curve of GFRCYS was larger compared with that of GFRMDRD and GFREPI (0.78 vs. 0.68 and 0.66, P=0.001 and P<0.001) for predicting the presence of poor collateralization, along with a net reclassification improvement of 15.0% and 20.1% (P=0.025 and P=0.002). After adjusting for possible confounding variables, a GFR<90 mL/min/1.73m2 estimated with the cystatin C- based formula was more independently associated with poor collateralization (OR:6.21 vs. 2.86 and 2.36, P=0.042 and P=0.015). In contrast, GFRCYS, GFRMDRD, and GFREPI were similar for assessing coronary collateralization in non-diabetic patients. Conclusions: Cystatin C-based definition of renal dysfunction indicates a potential better clinical utility than creatinine-based equations for predicting poor Cystatin collaterals in diabetic atherosclerotic patients.