Systemic arterial compliance is decreased in newly-diagnosed patients with coronary heart disease: Implications for prediction of risk

Background. Proximal aortic compliance has been shown to be lower in coronary heart disease (CHD) patients compared with healthy matched controls. Assessment of proximal systemic compliance can be performed non-invasively and, therefore, the measurement of proximal compliance may be useful as a risk marker of the likelihood of significant coronary disease. Methods. Systemic arterial compliance (SAC) and regional aortic stiffness (β-index of the transverse arch) were measured non-invasively in a group of 20 newly-diagnosed CHD subjects and compared with an otherwise matched control group. These measurements were used to obtain an estimate of the predictive power of mechanical indices in CHD. Results. Significant differences between subjects and controls were found in both SAC and regional aortic stiffness in the absence of differences in blood pressure. Use of log(e)(SAC) resulted in correct identification of 60% of the cases and 85% of controls. Use of both mechanical indices improved discrimination to 100% for cases, and 87% for controls. Equal likelihood points (case/control), derived from the estimated group distributions, corresponded to log(e)(SAC) = -1.30 and log(e)(β-index) = 2.25. Arbitrarily requiring a 20:1 odds ratio of lack of disease required log(e)(SAC) > -1.40 and log(e)(β-index) < 2.25. For the same odds ratio of presence of disease, log(e)(SAC) < -2.70 and log(e)(β-index) > 3.50 were required. Conclusion. Non-invasive assessment of aortic elastic properties is not a definitive diagnostic test for CHD. Our results demonstrate the potential for repeatable, non-invasive methods of assessment of arterial mechanical properties to provide useful additional information for the overall assessment of an individual's cardiovascular risk. Our results also provide a basis for selecting arbitrary break points by which to group subjects in prospective studies.