Peripheral arterial tonometry cannot detect patients at low risk of coronary artery disease

BACKGROUND Endothelial dysfunction precedes coronary artery disease (CAD) and can be measured by peripheral arterial tonometry (PAT). We examined the applicability of PAT to detect a low risk of CAD in a chest pain clinic. METHODS In 93 patients, PAT was performed resulting in reactive hyperaemia (RHI) and augmentation (AIx) indices. Patients were risk classified according to HeartScore, Diamond and Forrester pretest probability (DF), exercise testing (X-ECG), and computed tomography calcium scoring (CCS) and angiography (CTA). Correlations, risk group differences and prediction of revascularisation within 1 year were calculated. RESULTS RHI correlated with HeartScore (r = - 0.21, p = 0.05), AIx with DF (r = 0.26, p = 0.01). However, both were not significantly different between normal and ischaemic X-ECG groups. In addition RHI and AIx were similar between low risk as compared with intermediate-to-high risk, based on risk algorithms (RHI: 1.98 (0.67) vs 1.94 (0.78); AIx: 0.0 (21) vs 5.0 (25); p = NS), or CCS and CTA (RHI: 1.99 (0.58) vs 1.89 (0.82); AIx: - 2.0 (24) vs 4.0 (25); p = NS). Finally, RHI and AIx failed to predict revascularisation (RHI: OR 1.42, CI 0.65-3.1; AIx: OR 1.02, CI 0.98-1.05). CONCLUSIONS PAT cannot detect a low risk of CAD, possibly because RHI and AIx versus X-ECG, CCS and CTA represent independent processes.