Getting to the Heart of the Matter: Most Detailed Study of Biracial Youth Explores Prehypertension, Cardiovascular Risk

Newswise — Two separate presentations of data at the American Society of Hypertension's Twenty Third Annual Scientific Meeting and Exposition (ASH 2008) underscore the need for aggressive management of cardiovascular risk in youth—including early race- and gender-specific health interventions related to obesity and prehypertension (a blood pressure reading between normal and high; when systolic blood pressure is between 120 and 139 or diastolic blood pressure is between 80 and 89 on multiple readings).

The findings are from the Bogalusa Heart Study, a long-term epidemiologic study of the early natural history of arteriosclerosis in children and young adults from semirural biethnic (65% White; 35% Black) community in Bogalusa, Louisiana. It is the longest and most detailed study of biracial population of youth in the world.

"Since most cardiovascular (CV) events can be predicted long before symptoms develop, we undertook our study to better understand important factors related to race and cardiovascular disease, and today, we highlighted two key findings," said Gerald Berenson, MD, Professor of Cardiology at the Tulane Center for Cardiovascular Health in New Orleans. "First, prehypertension puts our youth at greater risk for future CV events, and this condition is more common in Blacks, with Black females having greater
hypertensive levels than their White counterparts. Secondly, study results show that the shape of the heart—affected largely by obesity—predicts the shape of things to come. In this case, dilated left ventricular (LV) enlargement, present since early childhood, can lead to future clinical occurrences of heart failure, stroke and other CV events. In adults, Blacks had higher odds for LV enlargement."

Prehypertension in Youth
The Bogalusa Heart Study was in part undertaken to evaluate the importance of prehypertension with CV risk factors and adverse silent cardiac and vascular changes in young adults. In this study cohort of 1,379 biracial young adult population, 827 (60%) had normal blood pressure (normotensive), 377 (27%) were prehypertensive and 175 (13%) were hypertensive. Echocardiography and carotid ultrasonography were performed on 1,379 adult subjects (age range 20 to 44 years, average 36 ± 5 years, 43% male, 70% White).

Significant gender and race differences were evident among groups; 35% of men had prehypertension compared with 22 % of women. Prehypertension was present in 29%, of Blacks and in 27% of Whites. Black males were more hypertensive than their White counterparts (28% vs. 12%). The prevalence of prehypertension among White and Black males were similarly high (35%), but Black females were more prehypertensive than White females (25% vs 20%).

Importantly, compared to those with normal blood pressure, prehypertensives had a greater adverse cardiovascular risk factor profile, including increased body mass index (BMI), pulse pressure, heart rate x systolic blood pressure product, waist circumference, fasting glucose, insulin, low density lipoprotein (LDL) cholesterol, total/high density lipoprotein (HDL) cholesterol ratio and triglycerides. Prehypertensive subjects were also more likely to be obese or diabetic. Male gender and body mass index equally and significantly contributed to the prehypertension status in both Whites and Blacks. In addition, prehypertensives had significantly greater left ventricular (LV) mass index, LV internal diameter, and carotid artery intima-media thickness, evidence of underlying CV structural disease.

"The public should not assume that at blood pressure levels below designated ‘hypertension’ are innocuous," said Berenson. "These obsevations give a compelling reason for pursuing preventive, personalized intervention strategies at an early age in order to evaluate obesity and underlying CV disease risk factors."

Obesity Determines Heart Shape—and Future CV Risk—in Young Adults
Cardiac shape changes over time, and structural abonormalities are associated with such CV risk factors as obesity, hypertension, and diabetes. In the Bogalusa Heart Study, researchers investigated the distribution of left ventricular (LV) geometric remodeling based on a bi-racial cohort of young adults and assessed their association with individual CV risk factors in both adulthood and childhood.

There were 824 Black and White adult subjects in this study group (ages 24 to 44 years, average 36; 41% men, 69% white) who had CV risk-factor variable data from their childhood (24 years earlier; age range 5 to 18 years, average 12). The prevalence of echocardiographic LV hypertrophy was 6.6%. Eccentric (dilated) type of LV hypertrophy and concentric (thickening) remodeling were the most commonly encountered LV geometric changes in this young adult population (4.7% vs. 1.8% for concentric type of LV hypertrophy). In adulthood, subjects with eccentric and/or concentric LV hypertrophy compared with normal geometry were more likely to be obese and/or diabetic and had significantly increased BMI, waist circumference, systolic and diastolic blood pressures, glucose, insulin, hemoglobin A1c, total/high-density lipoprotein cholesterol ratio, triglycerides, and urinary albumin-creatinine ratios. Both adulthood and childhood BMI was the significant determinant of eccentric LV hypertrophy. The presence of diabetes mellitus in adulthood and diastolic blood pressure in childhood were significant predictors of concentric LV hypertrophy. In adults, Blacks had higher odds for concentric LV hypertrophy, which related to diabetes and systolic blood pressure.

"Early screening practices can help us predict and potentially prevent the world's deadliest killers," said Berenson. "Because the eccentric (dilated) type of LV hypertrophy was more frequent and obesity since childhood was the only consistent and significant determinant of adverse cardiac remodeling, findings can be generalized to understand the nature of CV risk in prediction of future clinical occurrences of heart failure, stroke, and other CV events."

About the American Society of Hypertension
The American Society of Hypertension (ASH) is the largest U.S. professional organization of scientific investigators and healthcare professionals committed to eliminating hypertension and its consequences. ASH is dedicated to promoting strategies to prevent hypertension and to improving the care of patients with hypertension and associated disorders. The Society serves as a scientific forum that bridges current hypertension research with effective clinical treatment strategies for patients.