Predictive value of endothelial function by noninvasive peripheral arterial tonometry for coronary artery disease

Background Endothelial dysfunction is a key step in the initiation and progression of atherosclerosis and subsequent cardiovascular complications. We examined whether peripheral endothelial function, as assessed by fingertip reactive hyperemia-peripheral arterial tonometry (RH-PAT), can provide additional clinical value to traditional risk factors for cardiovascular diseases in predicting coronary artery disease (CAD). Methods We included 118 stable patients who were referred for coronary angiography for chest pain evaluation or due to abnormal stress test results. A natural logarithmic value of the RH-PAT index (Ln-RHI) was obtained before cardiac catheterization by an independent operator. Significant CAD was defined as luminal stenosis of at least 70% (≥50% at left main) and/or fractional flow reserve of up to 0.80 in one or more major coronary arteries or their major branches. Results Levels of Ln-RHI were significantly lower in patients with CAD (n=60) compared with patients without CAD (n=58; 0.69±0.29 vs. 0.88±0.27, P<0.001). Ln-RHI was significantly associated with CAD independent from traditional risk factors (odds ratio for a 0.1 decrease in Ln-RHI=1.25, 95% confidence interval: 1.04-1.52, P=0.01). The net reclassification index was improved when Ln-RHI was added to traditional risk factors (0.62, 95% confidence interval: 0.27-0.97, P=0.001). Conclusion Peripheral endothelial function, as assessed by RH-PAT, improved risk stratification when added to traditional risk factors. RH-PAT is potentially useful for identifying patients at high risk for CAD.