Abstract-Increased renal restive index (RI) measured using Doppler ultrasonography has been shown to correlate with the degree of renal impairment in hypertensive patients. We investigated the prognostic role of RI in cardiovascular and renal outcomes. A total of 426 essential hypertensive subjects (mean age, 63 years; 50% female) with no previous cardiovascular disease were included in this study. Renal segmental arterial RI was measured by duplex Doppler ultrasonography. During follow-up (mean, 3.1 years), 57 participants developed the primary composite end points including cardiovascular and renal outcomes. In multivariate Cox regression analysis, RI was an independent predictor of worse outcome in total subjects (hazard ratio, 1.71 for 1 SD increase), as well as in patients with estimated glomerular filtration rate (eGFR) Ͻ60 mL/min per 1.73 m 2 (hazard ratio, 2.11 for 1 SD increase; PϽ0.01, respectively). When divided into 4 groups based on the respective sex-specific median levels of RI in the eGFR Ն60 and eGFR Ͻ60 mL/min per 1.73 m 2 groups, the group with eGFR Ͻ60 and high RI (male Ն0.73, female Ն0.72) had a significantly poorer event-free survival rate ( 2 ϭ126.4; PϽ0.01), and the adjusted hazard ratio by multivariate Cox regression analysis was 9.58 (95% CI, PϽ0.01). In conclusion, impairment of renal hemodynamics evaluated by increased RI is associated with an increased risk of primary composite end points, and the combination of high RI and low eGFR is a powerful predictor of these diseases in essential hypertension. In hypertensive patients with chronic kidney disease, RI evaluation may complement predictors of cardiovascular and renal outcomes. Key Words: cardiovascular disease Ⅲ renal hemodynamics Ⅲ ultrasonography Ⅲ hypertension Ⅲ predictor I n the past few years, there has been growing attention to markers of subclinical renal damage because they provide an accurate prediction of global cardiovascular outcome.1 Renal Doppler sonography permits noninvasive assessment of intrarenal hemodynamics in addition to evaluation of anatomic information. Intrarenal arterial waveforms recorded by Doppler sonography have been widely used to evaluate renal dysfunction.2,3 Previous studies have explored the capacity of resistive index (RI) calculated from blood flow velocity in vessels to predict the progression of renal function in patients with hypertension, 4 diabetes mellitus, 5 or chronic nephropathy. 6,7 In addition, histological studies demonstrated that RI not only reflects changes in intrarenal perfusion and renovascular resistance but was increased in several pathological conditions, such as renal atherosclerosis 8 and tubulointerstitial damage. 9,10 In previous studies, the prognostic value of RI was examined only in chronic nephropathy, 6 elderly, 11 or heart failure patients
12; however, the results obtained were inconsistent. Thus, the status of RI as an independent cardiovascular risk marker remains to be elucidated. Estimated glomerular filtration rate (eGFR), which is a measure of the kidneys' ...