13 Nov Increased Aortic Stiffness May Explain Elevated Hypertension Risk in African Americans
MedicalResearch.com Interview with:
Wanpen Vongpatanasin, M.D.
Professor of Medicine
Norman & Audrey Kaplan Chair in Hypertension
Fredric L. Coe Professorship in Nephrolithiasis and Mineral Metabolism Research
Director, Hypertension Section,
UT Southwestern Medical Center
Dallas, TX 75390-8586
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Aortic stiffness is known to be associated with cardiovascular disease, including heart attack, stroke, and heart failure, possibly related to increase afterload to the left ventricle. Previous studies have not directly assessed proximal aortic function among ethnic minorities in the United States. We evaluated the multiethnic, population-based Dallas Heart Study participants (N=2544, 54.2% women, 49.7% Black) who underwent cardiovascular magnetic resonance imaging (CMR) at 1.5 Tesla. Aortic stiffness and characteristic impedance (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.
MedicalResearch.com: What are the main findings?
Response: We found that, compared with Whites, both Blacks and Hispanics had higher levels of aortic arch PWV (4.25, 95% CI 4.15-4.35, vs. 4.72, 95% CI 4.64-4.81, vs. 4.48, 95% CI 4.33-4.63 m/sec, respectively, both p < 0.05 vs. White), and Zc (64.9, 95% CI 63.3-66.6, vs. 75.6, 95% CI 74.0-77.2, vs. 70.1, 95% CI 67.6-72.8 dyne*sec/cm5, respectively, both p < 0.01 vs. White) after adjustment for age, age squared, sex, BMI, mean arterial blood pressure (BP), antihypertensive treatment, heart rate, total cholesterol, diabetes mellitus, and smoking. Compare with Hispanics, Blacks also had higher level of both PWV and Zc (both p < 0.01).
MedicalResearch.com: What should readers take away from your report?
Response: Our demonstration of ethnic differences in arterial stiffness is an important step in understanding the mechanisms that mediate ethnic differences in cardiovascular disease. Since aortic stiffness is also found to contribute to development of hypertension, our study provides a potential explanation for excess risk of hypertension and resultant organ complication in African-Americans, who are at particularly high risk of cardiovascular disease.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Further studies are needed to determine mechanisms underlying our observation. Potential factors included greater sodium or phosphate intake among African-Americans and Hispanics, lower intake of potassium, and genetic differences in vascular calcification or collagen content.
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