Comparison of Invasive vs Noninvasive Pulse Wave Indices in Detection of Significant Coronary Artery Disease: Can We Use Noninvasive Pulse Wave Indices as Screening Test

Various non-invasive techniques to assess the indices of arterial stiffness, such as augmentation Index were used previously to detect coronary artery disease (CAD). We studied two indices of arterial stiffness analyzed from pulse contour analysis—reflection (RI) and stiffness index (SI) both by noninvasively using plethesmography and invasively from radial artery along with ECG to detect CAD and its severity. 56 patients with a mean age of 52.62 ∓ 8.3 yrs undergoing coronary angiogram transradially either for the diagnosis or exclusion of CAD participated in this study. Significant coronary artery disease (CAD) is defined as greater than 50% stenosis in at least one epicardial coronary artery (ECA). Scores of 0, 1, 2, and 3 was given for normal (no CAD group), significant CAD in one ECA, two ECA and all three ECA respectively. 17 patients had normal ECA, 15 patients had score 1, 13 patients had score 2, and 11 patients had score 3. By noninvasive method, the mean value of RI for no-CAD group was 37.82% ∓ 7.3% vs CAD group 73.09% ∓ 10.09% (p 0.05) or SI (p > 0.05). By invasive method RI (p = 0.0056) and SI (p = 0.0068) showed statistically significant correlation in detection of CAD but not for the severity. In conclusion, reflection and stiffness index have a significant difference in patients with CAD and CAD patients receiving medication. However, the difference between these parameters in varying grades of CAD is not significant