gms | German Medical Science

Pulse wave analysis has been advocated as a simple means to estimate arterial stiffness. Aortic stiffness measured by aortic pulse wave velocity (PWV) is a powerful predictor of cardiovascular disease. We compared indices of arterial stiffness derived from the digital volume pulse (stiffness index, SI) and from the transformed radial pressure pulse (augmentation index, AIx) with aortic PWV and Framingham estimate of coronary heart disease (CHD) risk. The performance of these measurements for detecting high risk subjects was assessed using receiver operating characteristic (ROC) curves. High risk subjects were defined as those for whom Framingham 10-year CHD risk was greater than 15% (as recommend by the Joint British Societies). Measurements were obtained in 101 subjects (30 women) with no clinical evidence of CHD. Mean (±SD) values of Framingham risk factors were: age: 44±13 years, systolic blood pressure (SBP): 138±23 mmHg, total-cholesterol (T-Chol): 5.3±1.1 mmol/L, HDL-cholesterol: 1.35±0.37 mmol/L. 16% of subjects were smokers, 4% diabetic and 14% had ECG evidence of left ventricular hypertrophy. Aortic PWV was obtained by carotid-femoral tonometry (Sphygmocor, Atcor, Australia), AIx by radial tonometry using the radial-aortic transfer function and SI was determined from the digital pulse waveform (PulseTrace, Micro Medical, UK).

SI and AIx were correlated with PWV (R = 0.44, P<0.001 and R=0.27, P=0.006, respectively, each P<0.001). SI, AIx and PWV were independently correlated with age (R=0.45, 0.36 and 0.69 respectively, each P<0.001) and SBP (R=0.43, 0.38 and 0.41 respectively, P<0.001) but not with T-Chol, HDL, diabetic or smoking status or with LVH. AIx (corrected for age and SBP) was significantly greater in women than in men (P<0.001) but SI and PWV were similar in both sex. SI and PWV were significantly correlated with CHD risk (R=0.46, R=0.51, respectively, each P<0.001). The correlation was weaker for AIx (R=0.26, P=0.02). The area under the ROC curve was 0.72±0.08, 0.66±0.08 and 0.80±0.06 for SI, AIx and PWV respectively.

SI and AIx are correlated with PWV and predict Framingham CHD risk but not as strongly as PWV. These measures may be useful in estimating risk, particularly in hypertensive subjects, but prospective studies will be required to verify this.