Research On Preventing Heart Disease In Older Adults Is Presented By University Of Pittsburgh At American Heart Association Meeting
PITTSBURGH, March 1, 2001 — New findings related to the development of heart disease in older adults will be presented by researchers from the University of Pittsburgh February 28-March 3 at the American Heart Association’s 41st Annual Conference on Cardiovascular Disease – Epidemiology and Prevention in San Antonio, Texas.
CORONARY ARTERY CALCIFICATION IN OLDER ADULTS RELATED MORE TO AGE THAN BASELINE RISKS
Coronary artery calcification (CAC) continues to increase in people into advanced old age and is more strongly related to age than to baseline risk factors, according to a study being presented by a University of Pittsburgh researcher.
Anne B. Newman, M.D., M.P.H., associate professor of geriatric medicine at the University of Pittsburgh and principal investigator, measured coronary artery calcification in 614 men and women with a mean age of 80 using electron beam tomography. The prevalence of clinical coronary vascular disease (CVD) was 33 percent, and another 33 percent had at least one marker of subclinical CVD.
Median CVD increased with age and was usually higher in men than in women, regardless of the presence or absence of clinical or subclinical CVD. No detectable CAC was found in six percent of men and 11 percent of women, but the proportion with a zero score decreased with age from 15 percent under age 80 to five percent of those over 80 years. Those with higher baseline scores were more likely to be Caucasian but did not differ in prevalence of baseline hypertension, diabetes or lipid levels.
ELEVATED HOMOCYSTEINE LEVELS CAN LEAD TO HYPERTENSION IN HEALTHY OLDER ADULTS
Healthy older adults can develop hypertension if they have high blood levels of homocysteine, a metabolite of the essential amino acid methionine, and the risk increases if they are overweight and smoke, according to an eight-year study conducted at the University of Pittsburgh Graduate School of Public Health.
“Elevated plasma homocysteine has been linked to arterial stiffness and the development of hypertension, but most of the previous research has been conducted using patients with renal disease and has been retrospective,” said researcher Rachel Wildman, M.P.H., who presented the findings. “This study is the first to assess homocysteine’s effect on hypertension in healthy older adults with normal baseline blood pressure, and to follow them prospectively. Our results show that 35 percent of healthy adults could develop hypertension within eight years, and high homocysteine levels may increase the risk.”
Ms. Wildman and her colleagues evaluated 187 men and women from the Carotid Assessment Program in the Elderly, a normotensive control population from the multi-center Systolic Hypertension in the Elderly Program. Median age was 71. Over an eight-year period of observation, 35 percent of the participants developed hypertension. Higher homocysteine levels, higher body mass index, current smoking and higher systolic blood pressure levels were factors independently associated with the development of hypertension.
“Homocysteine may contribute to hypertension through a direct effect on the elastic components of the arterial wall, or through an acceleration of the existing atherosclerosis,” said Ms. Wildman, “but additional research is necessary to determine the exact role that homocysteine plays in this process.”
SMALLER CHOLESTEROL PARTICLES POSE GREATER RISK THAN LARGER PARTICLES IN DEVELOPMENT OF ATHEROSCLEROSIS
Small-sized low density lipoproteins (LDLs, or “bad” cholesterol) and high numbers of these particles pose a greater risk for coronary calcification among post-menopausal women than do medium- or large-sized LDLs, according to a study conducted at the University of Pittsburgh Graduate School of Public Health.
“In post-menopausal women, the size and the concentrations of various-sized LDL particles may be a better predictor of atherosclerosis than the currently used standard cholesterol test, which measures the total amount of cholesterol carried by all the LDL particles, regardless of size,” said researcher Rachel Mackey, M.P.H. “Some explanations of why the smaller LDL particles may be more atherogenic are that they might pass more easily into the arterial wall or that they may be more susceptible to oxidation.”
Calcification of the coronary arteries occurs only where atherosclerosis or hardening of the arteries is also present. Thus, according to Ms. Mackey, calcification can signal the presence of atherosclerosis, which increases the risk of heart disease -- the leading killer of women in the United States.
The findings presented by Ms. Mackey were based on 287 healthy, post-menopausal women aged 57-65 from the university's Healthy Women's Study, which looked at cardiovascular risk factor changes over the course of menopause. In measuring LDL particle size, Ms. Mackey and her colleagues used a new laboratory test called the NMR LipoProfile (LipoMed, Inc.), which rapidly measures the size and concentrations of lipoproteins. NMR (nuclear magnetic resonance) technology works by measuring and recording radio signals emitted by lipoproteins and other blood fats transported in the blood. The signals vary according to the size of the particles. A computer reads the signals and determines the concentration of each lipoprotein subclass by the strength of its signal.