Atherosclerosis In Coronary Artery Reference Segments Complicated With Diabetes Mellitus: An Intravascular Ultrasound Study

【Objective】Pathologic studies indicate that the extent of coronary atherosclerosis is underestimated by visual analysis of angiographically normal coronary artery segments. This study evaluated the magnitude, patterns and clinical correlates of atherosclerosis in angiographically "normal" reference segments in patients with diabetes.【Material and Methods】The subjects with coronary artery disease(CAD) were enrolled in the First Affiliated Hospital of Kunming Medical College from January 2010 to January 2011.42 patients were enrolled. All patients were divided into 2 groups (diabetes mellitus group:16 patients; non-DM group:26 patients). Reference segment was defined as the frame with largest lumen area located within 10 mm from the minimal lumen area (MLA) frame without major intervening side branches.IVUS examination was not performed if severe vessel tortuousness, severe luminal narrowing precluding the insertion of the IVUS catheter or vessel occlusion were present. We measured the external elastic membrane area (EEM CSA), luminal area, plaque burden, eccentric index, the remodeling index and plaque composition. Categorical variables are expressed as numbers (percentages) and compared between groups with 2-tailed Chisquare test. When normally distributed, continuous variables are expressed as means (standard deviation) and compared with the 2-tailed t-test for independent samples.【Results】All reference segments from 44 vessels were measured atherosclerosis with intravascular ultrasound. The diabetes mellitus group had no statistically significant (p=0.162) difference compared with the non-DM group (7.80±1.27mm2 vs.8.23±1.52mm2; respectively). However, luminal area of reference segment in the diabetic group tended to be smaller. The diabetes mellitus group had significantly(p<0.05) bigger external elastic membrane area, plaque burden, eccentricity index and lesion length compared with the non-DM group. The linear correlation of plaque burden was well between reference segment and target lesion (r =0.665, p<0.001). There was a more significant negative remodeling in diabetes mellitus group (0.91±0.11 vs.1.02±0.09; p<0.01). A larger amount of fat composition was observed in the plaques of reference segment in diabetic patients (p =0.029).【Conclusion】Atherosclerosis in angiographically "normal" coronary artery reference segment also exists, particularly in diabetic patients. Coronary angiographic diagnosis in diabetic patients may be distorted due to a large plaque burden over longer vessel segments and the resulting absence of plaque-free reference segments. IVUS imaging illustrates coronary artery dimensions more accurately according to anatomic structures, so IVUS guidance of coronary angioplasty should be considered in diabetic patients for the evaluation of actual vessel diameter in order to assess the optimal stent size. In the early stage, diabetic patients need more aggressive medical therapy to delay or block the process of atherosclerosis.【Key words】coronary artery; atherosclerosis; intravascular ultrasound; reference segment; diabetes mellitus.