Discrimination between different degrees of coronary artery disease using time-domain features of the finger photoplethysmogram in response to reactive hyperemia.

•PPG combined with ECG in FMD test can discriminate between different degrees of CAD.•PPG from both index fingers and angiograms were recorded from 48 patients.•Subjects are regrouped as high-risk (2VD, 3VD) and low-risk (NC, Mild, SVD) groups.•k-NN gives an accuracy of 81.5%, a sensitivity of 82.0% and a specificity of 80.9%.