BACKGROUND: Progression of coronary artery disease(CAD) is highly unpredictable, and follows a nonlinear course. In previous reports, progression was related to acute myocardial infarction and cardiac death. The present study was designed to assess the characteristics of progression of CAD and to ditermine the predictors for progression. METHODS: The present study included 41 patients(age 55+/-9 years ; male/female=36/5) with CAD who underwent coronary angiography at least twice(interval : mean 26 months), and patients who underwent coronary angioplasty of coronary bypass surgery before the 2nd angiograms were excluded from analysis. The coronary arterial bed was divided into 15 segments according to American Heart Association(AHA) committee report. We measured both % stenosis and minimal diameter of the lesions, and divided the lesions into four Ambrose's morphological categories. Progression was considered to be present if one of the following changes had occurred : increase in % stenosis of lesions by> or =20%, decrease in minimal diameter by> or =0.5mm, or any new occlusion. For the purpose of detecting predictors we investigated clinical history(smoking, hypertension, obesity, and DM), angiographic findings(numbers of diseased vessels and lesions), and biochemical study (total cholesterol, LDL, HDL, triglyceride, uric acid, and albumin). RESULTS: Altogether, 32 patients(78%) showed progression, and regression was present in 11 patients(27%). Six patients had both progressed lesions and regressed lesions. Progression occurred most frequently in segments with stenosis of 1% to 25% at initial arteriogram. Progression occured in increasing order in proximal right coronary artery, mid-LAD, and proximal LAD. There was no significant differences in progression among four Ambrose's morphologic categories. 59(10%) of the analyzable 589 segments had progressed, 19 them upto occlusion, and 7 segments became infarct related artery. In 5(71%) of 7 cases of new myocardial infarction it occurred in segments with< or =75% stenosis at initial arteriogram. The analysis selected two independent predictors for progression: uric acid and numbers of lesions> or =20% stenosis. CONCLUSION: The present study suggests that progression of CAD occurred most frequently in minimally stenotic lesions and that about two thirds of acute myocardial infarction occurred from insignificantly stenotic lesion. Uric acid level and numbers of lesions> or =20% stenosis were selelcted as the independent predictors of coronary disease progression.