Safety Aspects in Carotid Artery Stenting - Is Flow Reversal the Solution? Johan Formgren Head of Peripheral Vascular Interventions, Department of Medical Imaging, Södersjukhuset AB, Stockholm
Since the publication of the Endarterectomy versus Angioplasty in Patients with Symptomatic Severe Carotid Stenosis (EVA-3S) and Stent-supported Percutaneous Angioplasty of the Carotid Artery versus Endarterectomy (SPACE) studies, doubts have been raised regarding the safety of CAS as an alternative carotid intervention to CEA.
Keith C Ferdinand Morehouse School of Medicine, Emory University, and Association of Black Cardiologists, Inc.; , Verna L Welch Cardiovascular Research Institute, Morehouse School of Medicine
Hypertension is a major contributor to the global disease burden and is one of the leading preventable causes of premature death worldwide.1 In the US, a disproportionate burden of hypertension and its associated complications—including coronary heart disease, heart failure, stroke, and end-stage renal disease and cardiovascular disease mortality—affect African-Americans (also referred to as US blacks).2 This excess burden of hypertension among African-Americans has been recognized since early in the 1900s and explains a substantial portion of health disparities in this population.3–5 The goal of this review is to provide an update of the current research on hypertension in African-Americans through a brief description of the epidemiology, pathophysiology, and management of hypertension.
Epidemiology
The rates of hypertension in various populations of African ancestry have geographical variances related to high sodium intake, low potassium intake, obesity, and inactivity. As such, African-Americans have one of the highest rates of hypertension worldwide—much higher than other populations of African origin.6 Compared with white Americans, hypertension is not only more prevalent in this population, it is also observed at an earlier age, has greater severity, and is accompanied by a disproportionate level of target organ damage (1.8-fold higher rate of stroke, 4.2-fold higher rate of endstage renal disease, 1.7-fold higher rate of heart failure, 1.5-fold higher rate of coronary heart disease mortality).2
Hypertension represents a risk across the lifespan. Perhaps the most alarming epidemiological data regarding hypertension among African- Americans come from studies of children and adolescents. Data from the Bogalusa Heart Study, a bi-racial cohort study conducted in the state of Louisiana including approximately 3,500 school-age children, demonstrate that beginning at age 10, African-American children had significantly higher blood pressure (BP) values than did white children.7,8 Data from other studies confirm that elevated blood pressure begins as early as pre-adolescence and children who remain in the highest 90th blood pressure percentile are more likely to evolve toward permanent hypertension or early target organ damage in young adulthood.9–11
The prevalence of hypertension varies by both race and gender, with the highest prevalence rates observed among African-American women. Although not specifically described by race/gender, the age-adjusted prevalence of hypertension in the 2003–2004 National Health and Nutrition Examination Survey (NHANES) was 39.1% for African-Americans compared with 28.5% for white Americans.12 Earlier race-/gender-specific data from NHANES 1999–2004 indicate that the age-adjusted percentage of persons with hypertension, defined as >140/90mmHg or taking antihypertensive medication, has actually increased in the US, to 41.4% for African- American females and 39.0% for African-American males versus 28.5% for non-Hispanic white males and 28.0% for non-Hispanic white females.2
The burden of death related to hypertension is significantly higher in African- Americans. In 2004, the overall death rate from hypertension was 17.9 compared with 49.9 and 40.6 for African-American men and women, respectively.2 These higher mortality rates are consistent with poor levels of BP control among African-Americans. Despite 66.4% of African-Americans being aware of their hypertension and 55% treated, only 28.9% achieve BP control compared with 33.1% controlled in the overall population.12 In addition to poor rates of BP control, US blacks have been under-represented in clinical trials, limiting the usefulness of trial results in guiding pharmacological therapy in management of hypertension among African-American patients. However, recent trials have attempted to recruit larger numbers of African Americans and may provide insight into pharmacological management in this population.
Pathophysiology
Researchers have noted that some African-Americans may have unique pathophysiology related to a greater prevalence and severity of hypertension, including factors involving the epithelial sodium channels, renin-angiotensin-aldosterone system (RAAS), adrenergic receptors, nitric oxide pathways, and transforming growth factor hyperexpression.
Keith C Ferdinand, MD, FACC, is Adjunct Clinical Professor at the Morehouse School of Medicine,
Clinical Professor in the Cardiology Division at Emory University, and Chief Science Officer of the
Association of Black Cardiologists (ABC), Inc. Board-certified in internal medicine and
cardiovascular disease, he is also a diplomat certified in the subspecialty of nuclear cardiology,
an American Society of Hypertension-certified specialist in clinical hypertension, and a Fellow of
the American College of Cardiology. Prior to September 2005, he was Medical Director at
Heartbeats Life Center in New Orleans, Louisiana. He presently resides in Atlanta, Georgia,
having been displaced in September 2005 from his native New Orleans by Hurricane Katrina,
which destroyed his cardiovascular center and severely damaged his home. In Atlanta, he is
Director of the ABC Hurricane Katrina Relief effort, known as the HOPE (Health Outreach and
Empowerment) Initiative. Dr Ferdinand received his medical degree from Howard University
College of Medicine.
Verna L Welch, PhD, MPH, is an Associate Professor of
Community Health and Preventive Medicine. She is Director of
the Cardiovascular Health Research Program of the
Cardiovascular Research Institute at Morehouse School of
Medicine. Dr Welch’s primary research interest is in the area of
cardiovascular health disparities. She is the recipient of multiple
research grants and a member of several professional
organizations. She earned her PhD in epidemiology from the
University of North Carolina at Chapel Hill and her Master of
public health in biostatistics from the Rollins School of Public
Health of Emory University.
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