Ethnic Difference in Proximal Aortic Stiffness: An Observation From the Dallas Heart Study.

OBJECTIVES: This study aims to compare ethnic difference in proximal aortic pulse wave velocity (PWV) and characteristic impedance (Zc).

BACKGROUND: Increased aortic stiffness is an independent predictor of target organ damage, incident hypertension, and all-cause mortality. However, previous studies have not directly assessed proximal aortic function in Blacks, the ethnic population with disproportionately high risk for incident hypertension and target organ complications.

METHODS: We evaluated the multiethnic, population-based DHS (Dallas Heart Study) participants (N = 2,544, 54.2% women, 49.7% Black) who underwent cardiac magnetic resonance at 1.5-T. Aortic stiffness and Zc were determined from aortic arch PWV and lumen area measurements. Linear regression was used to evaluate ethnic differences in proximal aortic wall stiffness using aortic arch PWV and Zc as dependent variables with and without adjustment for traditional cardiovascular risk factors. Because cardiac output was significantly higher in Blacks compared to Whites and Hispanics, additional comparisons of PWV and Zc were performed after adjustment for cardiac output and peripheral vascular resistance.

RESULTS: Compared with Whites, both Blacks and Hispanics had higher levels of aortic arch PWV (4.25, 95% confidence interval [CI]: 4.15 to 4.35 m/s, vs. 4.72, 95% CI: 4.64 to 4.81 m/s, vs. 4.48, 95% CI: 4.33 to 4.63 m/s, respectively, both p < 0.05 vs. White), and Zc (64.9, 95% CI: 63.3 to 66.6 dyne·s/cm5 , vs. 75.6, 95% CI: 74.0 to 77.2 dyne·s/cm5 , vs. 70.1, 95% CI: 67.6 to 72.8 dyne·s/cm5 , respectively, both p < 0.01 vs. White) after adjustment for age, age squared, sex, body mass index, height, mean arterial blood pressure, antihypertensive treatment, heart rate, total cholesterol, diabetes mellitus, and smoking. Compared with Hispanics, Blacks also had higher level of both PWV and Zc (both p < 0.01). Ethnic differences in PWV and Zc persisted after adjustment for cardiac output and peripheral vascular resistance.

CONCLUSIONS: In a multiethnic population-based-sample, Blacks and Hispanics had higher proximal aortic stiffness compared with Whites independent of blood pressure and relevant risk factors.