Background: The resistive index (RI) of the carotid artery is a hemodynamic parameter that depends on the degree of vascular resistance in hypertensive patients. The pulsatility index (PI) of the carotid artery was shown to be associated with microangiopathy in diabetic patients. In contrast to carotid intima-media thickness (IMT), no study has yet applied the carotid RI and PI to estimate coronary heart disease (CHD) risk.
Methods: Framingham risk scores (FRS) were determined for 62 patients (32 women; mean age 65 years (range 35-83)) with essential hypertension. Duplex sonography of the common carotid artery (CCA) was performed, with determination of RI, PI, and IMT.
Results: The mean FRS of all patients was 14.3% (range 1-30%), the mean IMT value of CCA was 0.89 +/- 0.23 mm, the mean RI was 0.71 +/- 0.07, and the mean PI was 1.46 +/- 0.39. FRS was found to have highly significant correlations with RI and PI (r = 0.47, P < 0.001 and r = 0.45, P < 0.001, respectively). The correlation between FRS and IMT was also significant (r = 0.41, P = 0.001). Multiple stepwise regression analysis showed that RI was an independent determinant of the risk of CHD.
Conclusions: Although RI indirectly reflected the atherosclerotic process, the correlation between RI and CHD risk was comparable to the well-known correlation between cardiovascular event and carotid IMT. Hence, carotid RI can be used as a tool for risk stratification in Taiwanese patients with essential hypertension.