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Study finds heart scans only useful in prescribing statins under certain conditions - Sunday 16 March 2014 - 12am PST

Saturday, 24 May 2014

As long as inexpensive statins, which lower cholesterol, are readily available and patients don't mind taking them, it doesn't make sense to do a heart scan to measure how much plaque has built up in a patient's coronary arteries before prescribing the pills, according to a new study by researchers at UC San Francisco.
The researchers created a statistical model to predict whether or not it made sense to do the scan, using data from the Multi-Ethnic Study of Atherosclerosis and other sources. They modeled the effects of statin treatment in 10,000 55-year-old women with high cholesterol and a 10-year risk of coronary heart disease of 7.5 percent. The model predicted that giving statins to all of them would prevent 32 heart attacks, cause 70 cases of statin-induced muscle disease and add 1,108 years to their cumulative life expectancy.
Then, they looked at how a coronary artery calcium test, or CAC test, could be used to target statin therapy only to those women who the CAC test showed were at heightened risk of coronary heart disease. They found that this strategy would save money on statin costs and expose fewer women to side effects from statins but would not prevent as many heart attacks. Moreover, the test itself exposes the women to a small risk of radiation-inducedcancer and costs about $200 to $400 per scan.
The researchers concluded that as long as the price of a statin remained low - 13 cents a pill - and did not reduce quality of life for patients, it was not cost-effective to perform a CAC test to target the drug therapy only toward those at increased risk of coronary heart disease. But if the price of the pill were more expensive - $1 or more - or if taking them reduced patients' quality of life, then it did make sense to use the CAC test.
The result is somewhat surprising, given all the evidence that has accumulated over the last decade that the test strongly predicts heart attacks, said the lead author, Mark Pletcher, MD, MPH, an associate professor of epidemiology and biostatistics, and medicine, at UCSF. The study was published online in Circulation: Cardiovascular Quality Outcomes.
Traditional prediction models, such as the Framingham-based risk equations, work imperfectly, and doctors have long sought better ways to figure out which patients would benefit most from taking statins, which can cause side effects, such as muscle aches, decreased cognitive function and cataracts.
"The prevailing wisdom is that if you have a test that predicts heart attacks, you should use it," Pletcher said. "But even a test that is strongly predictive of future events, like a coronary artery calcium scan, does not itself improve outcomes. If it is used to keep some people off of statins that would otherwise take them, then fewer people will get protection from using statins, and more people will have heart attacks."
The study incorporated data from MESA and many other sources to create a cost-effectiveness model. The researchers tested whether changing the other model inputs made a difference, and it turned out that the only critical factors were the cost of statins and the degree to which they decreased quality of life for patients.

New gene-scanning approach finds link to heart attack risk 'hiding in plain sight'

As scanning genomes for disease-related gene variations becomes more commonplace, scientists are pinpointing gene variations that change the way proteins function. Using this approach, a new study found a previously unknown gene variation that appears to make blood lipid levels healthier in humans and reduce risk of heart attacks.
The study researchers, from the University of Michigan and the Norwegian University of Science and Technology, report their findings inNature Genetics. They hope the discovery will lead to new ways of testing or treating patients with high cholesterol and other lipid disorders.
They explain that by looking at the genetic code differently - such as looking for how it influences the way proteins behave - they found the gene hiding in plain sight in previous searches for cardiovascular risk genes.
Senior author Cristen Willer, assistant professor of Internal Medicine, Human Genetics and Computational Medicine & Bioinformatics at the University of Michigan Medical School, says:
"While genetic studies that focused on common variations may explain as much as 30% of the genetic component of lipid disorders, we still don't know where the rest of the genetic risk comes from. This approach of focusing on protein-changing variation may help us zero in on new genes faster."
Several members of the team had been involved in earlier research in 2008 that looked at the same region of DNA and found it was linked to control of blood lipid levels.
But there was no suggestion at the time that this region of DNA contained specific genes with an obvious link to blood lipid levels.
Now, some 6 years later, the researchers scanned the genomes of over 5,600 Norwegians whose genetic, medical and health data was housed in a biobank. They focused on searching for variations in genes that change the way proteins function - in all, identifying over 80,000 coding variants.
From these, they came up with 18 candidate variants that they narrowed down to 10 that had links to blood lipid traits. Most of what they found was already known to be linked to cholesterol and other blood lipid levels.

Gene 'hiding in plain sight' in previous searches for cardiovascular risk genes

But one gene, TM6SF2, was a completely new find that had not surfaced before, although it had been "residing in a known genome-wide association study locus for lipid traits," write the authors.
A small percentage of the Norwegian participants who carried a particular variant of this TM6SF2 gene had noticeably healthier levels of blood lipids, and a significantly lower rate of heart attack.

Making gluten-free crackers with hemp flour and decaffeinated green tea leaves

A team of food scientists from University of Novi Sad in Serbia and Guelph Food Research Centre in Canada found that hemp flour, a by-product of cold-pressed hemp oil, in combination with decaffeinated green tea leaves could be used to develop a gluten-free snack cracker with functional properties. The study is in the current issue of Journal of Food Science published by the Institute of Food Technologists (IFT).
The market for gluten-free foods with functional properties is growing immensely across virtually all food categories on a global level. The need to replace wheat proteins, fibers, and minerals is very important in order to provide a better selection and more nutritious food for consumers that belong to this segment of the population. At the same time, the use of by-products of the food processing industry as a source of functional ingredients such as antioxidants, phenols, fibers and proteins is on the rise, which supports global sustainability.
A team of food scientists from University of Novi Sad in Serbia and Guelph Food Research Centre in Canada found that hemp flour, a by-product of cold-pressed hemp oil, in combination with decaffeinated green tea leaves could be used to develop a gluten-free snack cracker with functional properties. The study is in the current issue of Journal of Food Science published by the Institute of Food Technologists (IFT).
Hemp flour, as a by-product of cold-pressing oil process, is rich in proteins, fibers, phytochemicals, minerals, omega-6 and omega-3 essential fatty acids, and therefore a very valuable ingredient to use for food production. In terms of amino acid composition, hempseed proteins are comparable to the egg white and soy protein. Green tea leaves contain compounds that have been shown to have health benefits including cancerprevention of many types as well as decreasing LDL cholesterol levels.
The findings of this study, where hemp flour and decaffeinated green tea leaves were incorporated into crackers, suggest that consumers may benefit from consuming these gluten-free crackers with superior nutritional qualities in terms of high protein, crude fibers, minerals and essential fatty acids content and antioxidant properties.

The soluble fiber in oats helps lower total and LDL cholesterol but the cardiovascular health benefits of oats goes beyond fiber

Eleven top scientists from around the globe presented the latest findings on the powerful compounds found in oats in a scientific session titled, Physicochemical Properties and Biological Functionality of Oats, at the 247th Annual Conference of the American Chemical Society in Dallas, TX. Scientists described research on the diverse health benefits of oats and emphasized the growing evidence that the type of phenolic compound avenanthramide (AVE) - found only in oats - may possess antioxidant, anti-inflammatory, anti-itch and anti-cancer properties. The culmination of the studies suggests that oat AVEs may play an important role in protecting the heart.
Eating whole grains is consistently associated with a reduced risk of chronic disease, including cardiovascular disease. Most of the benefits have been attributed to the relatively high fiber, vitamin, mineral and phytochemical content of whole grains. Notably, the soluble fiber beta-glucan found in oats has been recognized for its ability to lower both total and low-density lipoprotein cholesterol (LDL-C).
"While the data to support the importance of oat beta-glucan remains, these studies reveal that the heart health benefit of eating oats may go beyond fiber," explains the session's presiding co-officer, Dr. Shengmin Sang of the Center for Excellence in Post-Harvest Technologies at North Carolina Agricultural and Technical State University. "As the scientific investigators dig deeper, we have discovered that the bioactive compounds found in oats - AVEs - may provide additional cardio-protective benefits."
Oat AVEs and Cardiovascular Disease Prevention
New research shows that oat AVEs may be partly responsible for the positive association between oats and heart health. Oliver Chen, Ph.D., of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, presented mechanistic data that demonstrated that the antioxidant and anti-inflammatory properties of AVEs likely contribute to the atheroprotection of oats.
Similarly, Mohsen Meydani, Ph.D., from the Vascular Biology Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, provided evidence that oat AVEs suppress the production of inflammatory cytokines associated with fatty streak formation in the arteries. In addition, oat AVEs appear to repress the process associated with the development of atherosclerosis.
Also on the program were scientists from Tufts University; Agriculture and Agri-Food Canada; PepsiCo Inc. R&D; the Institute of Food, Nutrition and Health in Zurich, Switzerland; the University of Minnesota; and Pennington Biomedical Research Center in Baton Rouge, LA. Their presentations reviewed their findings on the influence of the processing of oats on the glycemic response and bioactive composition, measuring the functionality of oat beta-glucan, the antioxidant potential of oat beta-glucan, the benefits of eating whole grains on chronic disease, and how oats may improve glucose control and lipid metabolism. This high-level scientific session revealed the far-reaching impact this simple grain plays in health promotion and disease prevention.

13 million more Americans deemed eligible for statins

New guidelines for using statins to treat high cholesterol and prevent cardiovascular disease are projected to result in 12.8 million more U.S. adults taking the drugs, according to a research team led by Duke Medicine scientists.
The findings for the first time quantify the impact of the American Heart Association's new guidelines, which were issued in November and generated both controversy and speculation about who should be given a prescription for statins.
In an analysis of health data published online in the New England Journal of Medicine, a team led by researchers at the Duke Clinical Research Institute found that most of the additional statin users under the new guidelines would be people older than age 60.
"We sought to do a principled, scientific study to try to answer how the new guidelines might affect statin use, particularly as they focused eligibility on patients with an increased risk of developing cardiovascular disease," said lead author Michael J. Pencina, Ph.D., professor of biostatistics at DCRI. "By our estimate, there might be an uptake in usage as a result of the guidelines, from 43.2 million people to 56 million, which is nearly half of the U.S. population between the ages of 40 and 75."
Pencina and colleagues from McGill University and Boston University used the National Health and Nutrition Examination Surveys (NHANES) for their analysis, focusing on 3,773 participants between the ages of 40-75 who had provided detailed medical information, including fasting cholesterol levels from blood tests.
The new guidelines expand the criteria for statin use to include people whose 10-year risk of developing cardiovascular disease, including stroke, is elevated based on a risk-assessment score.
The DCRI-led research team determined that the new guidelines could result in 49 percent of U.S. adults ages 40-75 being recommended for statin therapy, an increase from 38 percent.
The increase is much more pronounced among adults free of cardiovascular disease who are over age 60, with 77 percent recommended for statin use under the new guidelines vs. 48 percent under the previous standards. This contrasts with a modest increase from 27 percent to 30 percent among U.S. adults between the ages of 40 and 60.
Those most affected by the new recommendations are older men who are not on statins and do not have cardiovascular disease. Under the earlier guidelines, about 30.4 percent of this group of men between the ages of 60-75 were recommended for statin use. With the new guidelines, 87.4 percent of these men would be candidates for the therapy. Similarly for healthy women in this age group, those recommended for preventive statin use are projected to rise from 21.2 percent to 53.6 percent.
"The biggest surprise of the research was the age-dependent split for those affected by the new guidelines," Pencina said. "We anticipated that the impact would be age-dependent, but not to the degree observed. The changes for both men and women in the older age groups where huge compared to those between the ages of 40 and 60."
Overall, of the 12.8 million additional U.S. adults recommended for statin use under the new guidelines, 10.4 million are people who would be prescribed the drugs for preventive care. Of those preventive users, 8.3 million would be people over the age of 60.
The analysis also projects that an estimated 1.6 million adults previously eligible for statins under the old guidelines would no longer be candidates under the new standards. This group included primarily younger adults with elevated cholesterol but low 10-year risk of cardiovascular disease.
Pencina said an important limitation of the study is the necessary assumption that the new guidelines would be followed to the letter; in real life, people may be recommended for statins but decline to start the therapy.
"Recommendations are just that - recommendations," Pencina said. "These guidelines correctly call for a thorough discussion between the doctor and patient about the risks and benefits of statins. It's not like everybody who meets the guidelines should all of a sudden go on statins."

Structure decoded of cholesterol transporter

The word "cholesterol" is directly linked in most people's minds with high-fat foods, worrying blood test results, and cardiovascular diseases. However, despite its bad reputation, cholesterol is essential to our wellbeing: It stabilizes cell membranes and is a raw material for the production of different hormones in the cell's power plants - the mitochondria. Now, for the first time, scientists in Gottingen have solved the high-resolution structure of the molecular transporter TSPO, which introduces cholesterol into mitochondria. This protein also serves as a docking site for diagnostic markers and different drugs, such as Valium. The detailed knowledge of its three-dimensional shape and function opens up new diagnostic and therapeutic perspectives.
Not only are mitochondria the most important energy supplier in living cells. They also produce steroid hormones such as testosterone and oestradiol, which control many processes in the body. The raw material for the production of steroid hormones is cholesterol, which must first be transported into mitochondria across two membranes. This difficult task is carried out by a molecular transport protein named TSPO in the outer mitochondrial membrane. Using nuclear magnetic resonance spectroscopy, two teams working with the Göttingen-based scientists Markus Zweckstetter and Stefan Becker have now shown the complex three-dimensional structure of the protein "at work" in atomic detail.
The researchers achieved this methodical breakthrough by applying an ingenious trick: In their experiments, they coupled the transporter to an important diagnostic marker called PK11195; it was this complex that first gave the scientists analyzable results. In fact, the TSPO structure delivers more than just clues about how cholesterol is transported into the mitochondria. "We now also have a much better understanding of how TSPO recognizes and binds to diagnostic markers and drugs", explains Markus Zweckstetter, head of research groups at the German Center for Neurodegenerative Diseases (DZNE), at the Max Planck Institute for Biophysical Chemistry, and at the Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB) at the University Medical Center of Göttingen (UMG).
TSPO has long been successfully used in diagnostics and treatment of a number of diseases. "When the brain is injured or inflamed, its cells produce more TSPO. This fact is used in the diagnosis of neurodegenerative diseases such as Parkinson's and Alzheimer's", explains Stefan Becker, a protein chemist and Max Planck researcher who works next door to Zweckstetter.
Physicians also use radioactively tagged molecules such as PK11195 to visualize inflamed areas of the brain. A detailed understanding of how TSPO binds to such markers opens up novel paths for diagnostic imaging and could constitute an important step along the way to early detection of such diseases and inflammations.
TSPO also binds several medicinal drugs such as diazepam, also known by the trade name of Valium. Not only is diazepam a widely prescribed sedative; it is also used in the treatment ofanxiety and epileptic seizures. The Göttingen researchers hope that detailed information about the transporter's structure will help to develop new TSPO-binding drugs.

Seasonal fluctuations in cholesterol levels

Cholesterol levels fluctuate based on the time of year with more unfavorable lipid profiles seen in the colder months, a trend that may be driven by related behavior changes, according to research presented at the American College of Cardiology's 63rd Annual Scientific Session.
While previous studies have shown that heart attacks and heart-related deaths increase during the winter months, researchers at Johns Hopkins Ciccarone Center for the Prevention of Heart Disease were interested in finding out whether cholesterol parameters might follow a similar pattern among a sample of 2.8 million adults - the largest study to look at seasonal lipid trends in U.S. adults to date. Abnormal cholesterol levels are a well-known cardiovascular risk factor.
"In this very large sample, we found that people tend to have worse cholesterol numbers on average during the colder months than in the warmer months - not by a very large amount, but the variation is significant," said Parag Joshi, M.D., cardiology fellow, Johns Hopkins Hospital, and lead investigator of the study. "It confirms findings from smaller studies and raises a lot of interesting questions, including what might be driving these [fluctuations]."
Researchers caution these findings do not mean patients should have their cholesterol checked more frequently or at certain times of the year; the data instead validates a clear seasonal pattern and underscores the need to pay attention to behaviors that are critical to minimizing cardiovascular risk.
"In the summer, we tend to get outside, we are more active and have healthier behaviors overall," Joshi said. "In the colder months, we tend to crawl into our caves, eat [fat-laden] comfort foods and get less exercise, so what we see is that LDL and non-HDL [bad cholesterol markers] are slightly worse. So you have a lipid signature of higher risk, but it's probably driven by a lot of behaviors that occur with the changing seasons."
Researchers speculate the shorter days of winter - and limited time spent outside - also mean less sun exposure and, subsequently, lower concentrations of vitamin D, which has also been associated with the ratio of bad to good cholesterol.
In this cross-sectional study, researchers analyzed lipid profiles in more than 2.8 million consecutive U.S. adults who were referred for testing by their doctors from 2006 to 2013. Samples were categorized by the time of year when cholesterol was measured and comparisons were made across the seasons. The study also compared gender-stratified lipids and the prevalence of national guideline-based goal attainment for low density lipoprotein (LDL), non-high density lipoprotein (non-HDL) and high lipoprotein (HDL) by season.
Total cholesterol, LDL cholesterol and non-HDL cholesterol levels were all higher in the winter than in the summer. LDL and non-HDL cholesterol were 4 mg/dL higher in men and 2 mg/dL higher in women during the colder vs. warmer months - a 3.5 percent and 1.7 percent increase, respectively. Non-HDL - total cholesterol minus good HDL cholesterol - is a more comprehensive marker of risk. Triglycerides were 2.5 percent higher in men during the winter compared with the summer. Women and men had variations in total cholesterol of approximately 2 mg/dL and 4 mg/dL, respectively, between the summer to winter. HDL did not vary much between seasons. Ratios of atherosclerotic risk were lowest in the spring and summer.
Attainment of National Cholesterol Education Program Adult Treatment Panel III goal LDL-C and non-HDL-C was more prevalent in the summer compared to the winter, while HDL-C was lowest in the fall. Authors also found that while women had more favorable risk profiles overall, a lower percentage of women met the ATP III targets compared to men. The difference between average cholesterol values in the fall and winter were not statistically significant.
Researchers said the distribution of these lipid profiles is analogous to a representative national sample of the current U.S. adult population. Samples were provided through a commercial lab (Artherotech, Birmingham, Ala.), which was not involved with the study or its analysis.
Interest for this study grew out of a sub-analysis from the PROVE-IT trial, a randomized controlled trial looking at the use of low- and high-dose statins after heart attack to see if there was a reduction in events. In this study, the authors also looked at cholesterol values over the year and by season. While this earlier study had similar findings, they were not statistically significant likely because of the smaller sample size, Joshi explained.
Despite these latest findings, he says more research is needed to further tease out what might be behind these seasonal variations.

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