Background : Aortic stiffness, central arterial stiffness, is believed to be an important risk factor of coronary artery atherosclerosis (CAA), as it directly affects coronary perfusion. But, little is known about the effect of the directly measured aortic stiffness during cardiac catheterization using pulse wave velocity (CPWV) on the development and progression of CAA. We assessed the following four aspects of the CPWV in relation to CAA. (1) The effect of CAA risk factors on CPWV. (2) The correlation of the non-invasively measured aortic stiffness by echocardiography using pulse wave velocity (EPWV) with CPWV. (3) The effect of CPWV on the development and severity of CAA and (4) on the progression of CAA and restenosis. Method : CPWV and degree of CAA were measured 360 patients and 132 of these patients underwent percutaneous coronary intervention (PCI). Follow-up measurement of CPWV and coronary angiography (CAG) will be complete by Sept. 2004. EPWV was measured in 100 patients. The severity and the progression of CAA were assessed by the presence of coronary artery disease, vessel score (number of diseased vessels), extent score (calculated from the number of diseased segments) and stenosis score (sum of the degree of stenosis of the all coronary artery segments), which were described in previous studies. Result : (1) Among the conventional risk factors of CAA, old age (>60) (p<0.001) and diabetes (p<0.001) were significantly associated with increased CPWV. Dyslipidemia was a significant risk factor for increased CPWV (p=0.004) only in patients who did not take statin. These three variables were significant risk factors for increased CPWV in both univariate and multivariate analysis. (2) EPWV showed significant but weak correlation with CPWV. (r=0.31, p=0.05) (3) CPWV showed significant effect on the presence of CAD (OR=1.024, 95% CI = 1.000 ~ 1.048) and vessel score (OR = 1.027, 95% CI = 1.011 ~ 1.043). (4) The effect of CPWV on the progression of CAA and restenosis will be determined by Oct. 2004. Conclusion : CPWV was associated with risk factors of CAA and was also an important risk factor of the development of CAA.