Aim: Isolated coronary artery ectasia (CAE) is an abnormal dilatation of the coronary artery which cause ischemia. RDW has been investigated in several cardiovascular disorders and has also been recently proposed as a predictive biomarker of adverse outcomes in patients with these conditions. We hypothesized that increased RDW would be associated with isolated CAE because both are associated with inflammation.
 Material and Methods: We studied 140 subjects, including 69 patients with isolated CAE, 71 patients with angiographically normal controls. Baseline clinical characteristics and laboratory findings, including RDW, were compared among two groups.
 Results: The level of RDW was significantly higher in isolated CAE than normal controls (14,36±1,61vs 13,59±1.57, p=0.005). In addition, the levels of glomerular filtration rate and creatinin, high density lipoprotein and low density lipoprotein were significantly lower in isolated CAE than normal controls (76,43±19,64 vs 100,36±18,3 and 0,9±0,28 vs 0,74±0,25, 43,39±10,09 vs 48,4±13,67, 121,36±32,05 vs 143,70±55,33 p=0,001, p=0,001, p=0,01, p=0,004 respectively). In a ROC curve analysis, a RDW value of 13,5 was identified as an effective cut off point for the discrimination of the presence or absence of isolated CAE (Area Under curve [AUC]: 0.71, CI 95%, 0.62-0.80, p