By Sharon Begley
Reuters
Thousands of heart attack victims every year have none of the notorious risk factors before their crisis - not high cholesterol, not unhealthy triglycerides. Now the search for the mystery culprits has turned up some surprising suspects: the trillions of bacteria and other microbes living in the human gut. 

In a study released on Wednesday, scientists discovered that some of the bugs turn lecithin - a nutrient in egg yolks, liver, beef, pork and wheat germ - into an artery-clogging compound called TMAO. They also found that blood levels of TMAO predict heart attack, stroke or death, and do so "independent of other risk factors," said Dr Stanley Hazen, chairman of cellular and molecular medicine at the Cleveland Clinic's Lerner Research Institute, who led the study.

That suggests a TMAO test could enter the arsenal of blood tests that signal possible cardiovascular problems ahead. "TMAO might identify people who are at risk (for heart attacks and strokes) despite having no other risk factors," Hazen said.

The discovery also suggests a new approach to preventing these cardiovascular events: altering gut bacteria so they churn out less TMAO.

The study joins a growing list of findings that link human "microbiota" - microbes in the gut, nose and genital tract, and on the skin - to health and disease. Research has shown that certain species of gut bacteria protect against asthma, for instance, while others affect the risk of obesity. Last week scientists reported that circumcision alters bacteria in the penis, and that this change (not only the anatomical one) helps protect men from HIV/AIDS, probably by reducing the number of bacteria that live in oxygen-free environments such as under the foreskin.

"It's very strong work," Dr Martin Blaser of New York University Langone Medical Center, a pioneer in studies of the microbiota, said of the TMAO study. "They show clearly that human microbiota play a key role in producing TMAO, suggesting new approaches to prevention and treatment" of cardiovascular disease.

Normal cholesterol, fatal heart attack
The new study builds on a 2011 discovery by the Cleveland Clinic team that, in lab mice, gut bacteria turn lecithin in food into TMAO, or trimethylamine-N-oxide, causing heart disease. In addition, they found, people with high levels of TMAO are more likely to have heart disease.

But that research left two questions hanging: Do human gut bacteria trigger the lecithin-to-TMAO alchemy, like those in mice? And do high levels of TMAO predict heart attacks and stroke in people many years out, not simply mark the presence of cardiovascular disease at the time of the blood test?

To answer the first question, Hazen and his colleagues had 40 healthy adults eat two hard-boiled eggs, which contain lots of lecithin. Just as in lab mice, TMAO levels in the blood rose. After a week of broad-spectrum antibiotics, however, the volunteers' TMAO levels barely budged after they ate eggs, the researchers reported in the New England Journal of Medicine.

"That showed that the intestinal bacteria (which antibiotics kill) are essential for forming TMAO," said Hazen.

Next, to see whether TMAO predicts cardiovascular events, the researchers measured its levels in 4,007 heart patients. After accounting for such risk factors as age and a past heart attack, they found that high levels of TMAO were predictive of heart attack, stroke and death over the three years that the patients were followed.

Moreover, TMAO predicted risk more accurately than triglyceride or cholesterol levels, Hazen said. And it did so in people without substantial coronary artery disease or dangerous lipid levels as well as in sicker patients.

Specifically, people in the top 25 percent of TMAO levels had 2.5 times the risk of a heart attack or stroke compared to people in the bottom quartile.

The reason TMAO is so potent is that it makes blood cholesterol build up on artery walls, causing atherosclerosis (hardening of the arteries) and, if the buildup ruptures and blocks an artery, stroke or heart attack.

Earlier this month, the Cleveland Clinic researchers reported that gut bugs also transform carnitine, a nutrient found in red meat and dairy products, into TMAO, at least in meat eaters. Vegetarians made much less TMAO even when eating carnitine as part of the study, suggesting that avoiding meat reduces the gut bacteria that turn carnitine into TMAO, while regular helpings of dead animals encourages their growth and thus the production of TMAO.

More studies are needed to show whether TMAO reliably predicts cardiovascular crises, and does so better than other blood tests. Experts disagree on how many people have no other risk factors but would be flagged by TMAO. Dr Gordon Tomaselli, chief of cardiology at Johns Hopkins University School of Medicine and past president of the American Heart Association, guesses it is less than 10 percent or so of the people who eventually have heart crises.

Someone with high levels of TMAO could reduce her cardiovascular risk by eating fewer egg yolks and less beef and pork. But someone with a two-eggs-a-day habit but low TMAO probably has gut microbes that aren't very adept at converting lecithin to TMAO, meaning she can eat eggs and the like without risking a coronary.

Just as statins control unhealthy cholesterol, prebiotics (compounds that nurture "healthy" gut microbes) or probiotics (the good bugs themselves) might control unhealthy TMAO. For now, however, no one knows which prebiotics or probiotics might do that. In one study, probiotics actually increased TMAO-producing bacteria - "not what you want," Hazen said.

Neither will popping antibiotics work: bacteria become resistant to the drugs. Developing compounds that crimp the ability of the bacteria to turn lecithin into TMAO, Hazen said, is more likely to succeed.

The future is unclear for a heart device aimed at preventing strokes in people at high risk of them because of an irregular heartbeat.

Early results from a key study of the device, Boston Scientific’s Watchman, suggested it is safer than previous testing found, but may not be better than a drug that is used to prevent strokes, heart-related deaths and blood clots in people with atrial fibrillation in the long term.

Atrial fibrillation, a common heart arrhythmia that affects millions of Americans, causes blood to pool in a small pouch. Clots can form and travel to the brain, causing a stroke.

The usual treatment is blood thinners like warfarin, sold as Coumadin and other brands. But they have their own problems and some are very expensive. The Watchman is intended to be a permanent solution that would not require people to take medication for the rest of their lives. It is a tiny expandable umbrella that plugs the pouch of blood, and is inserted without surgery, via a tube pushed into a vein.

A study four years ago indicated the device was at least as good at preventing strokes as warfarin, but the procedure to implant it led to strokes in some patients. The Food and Drug Administration required another test of its safety and effectiveness.

The new study, presented at a meeting of the American College of Cardiology, was led by Dr. David Holmes Jr. of the Mayo Clinic in Rochester, Minn. He and the clinic have a financial stake in the device.

The study involved 407 patients — 269 assigned to get the device and 138 to get warfarin. It had three main goals, and it clearly met the first on safety — strokes, heart-related deaths, blood clots and serious complications a week after implant or release from the hospital.

The other goals were assessed based on 88 patients who were tracked for 18 months after treatment. Strokes and blood clots occurred no more often with the device in the patients. However, the results suggested it would not prove better than warfarin at 18 months on a wider measure — a combination of strokes, heart-related deaths or clots.

Whether that will be enough to win FDA approval remains to be seen. Dr. Gordon Tomaselli, a Johns Hopkins University heart specialist and former president of the American Heart Association, said he was reassured that the device seems safer, and said it might be approved just for people who cannot tolerate blood thinners long term.

"It's a mixed result," he said. "There still are complications" but fewer of them in the new study.

Dr. Hadley Wilson, cardiology chief at Carolinas HealthCare System in Charlotte, enrolled patients in the new study and predicts the FDA will require even more testing.

"It would be difficult for approvability without further study," he said.

In the study, young stroke patients were about two times more likely to have cannabis detected in their urine compared to patients who were of a similar age, but hadn't had a stroke.

Although it's an illegal drug, "cannabis is generally perceived as having few serious adverse effects," said study researcher Dr. P. Alan Barber, a professor of clinical neurology at the University of Auckland in New Zealand. The findings suggest this may not be the case, Barber said.

However, the study only found an association, and not a cause-effect link. Although the researchers took into account each patient's age, gender and race, it's possible other factors might have been responsible for the link. For instance, many of the cannabis users also smoked tobacco, so it was impossible for the researchers to disentangle the effects of tobacco from those of marijuana. Further studies should be conducted to determine if marijuana smoking really can cause stroke, the researchers said.

Some physicians have reported cases of young patients with no risk factors for stroke experiencing one after heavy marijuana smoking, but few rigorous studies have investigated the link.

In the new study, Barber and his colleagues analyzed information from 160 patients between ages 18 to 55 who had suffered either an ischemic stroke, which occurs when a blood vessel to the brain is blocked, or a transient ischemic attack, also called a mini-stroke, which is caused by a temporary blockage of a blood vessel. For comparison, the study also included 160 people who visited the hospital for other reasons besides stroke.

Screening tests of patients' urine showed that 15.6 percent of stroke patients tested positive for marijuana use, compared to 8.1 percent of the other hospital patients. Cannabis users tended to be similar to nonusers in age, cause of stroke and risk factors for stroke and heart disease, such as high blood pressure and high cholesterol.

Cannabis use has effects on the heart and blood vessels that make a link with stroke possible, Barber said. For instance, cannabis use increases the risk of atherosclerosis, or the buildup of plaque in the arteries, which reduces blood flow and increases the risk of stroke, Barber said.

The study will be presented this week at the American Stroke Association's International Stroke Conference in Honolulu.

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Too few hours of sleep can raise the risk of stroke significantly, even among healthy, normal-weight people, a new study finds.

Attention, busy middle-aged folks. You may be healthy and thin, but if you habitually sleep less than six hours a night, you still could be boosting your risk of a stroke.

That’s the surprising conclusion of a new study being presented Monday at SLEEP 2012, the annual meeting of the nation’s sleep experts.

Getting too little shut-eye appeared to more than quadruple the risk of stroke symptoms among healthy, normal-weight people aged 45 and older, according to a study of some 5,600 people followed for up to three years.

“The really important take-home message is this: Don’t blow it off. Sleep is just as important as diet and exercise,” said Megan Ruiter, the University of Alabama at Birmingham researcher who led the study.

Experts recommend that healthy adults get between seven and nine hours of sleep a night. But about one in three U.S. workers regularly gets less than seven hours of snooze time, according to a recent government health report.

Ruiter and her colleagues reviewed data from some 30,239 people participating in the REGARDS study – Reasons for Geographic and Racial Differences in Stroke – sponsored by the National Institutes of Health.

Of those, they teased out some 5,666 people who were healthy at the start of the study – no history of stroke, stroke symptoms, so-called “mini-stroke” or transient ischemic attack, or elevated risk for sleep apnea and other sleep-disordered breathing problems.

“We eliminated all the people who were high risk,” Ruiter said.

But when they looked more closely at the sleep habits of those people and adjusted for their weight, they found what Ruiter said were unexpected results.

In people who fell into normal weight categories -- a body mass index of 18.5 to nearly 25 -- those who reported sleeping less than six hours a night were at about 4.5 times greater risk of developing stroke symptoms than whose who slept seven and eight hours a night. Surprisingly, that increase wasn't apparent in overweight or obese people who slept less.

“Our thought is that habitually sleeping less than six hours is kind of like a precursor,” said Ruiter. “It might kind of lead to some of these stronger and more severe risk factors later on.”

That’s dismaying news to Mark Wolfe, 49, a busy teacher, husband and father of four from Corvallis, Ore., who has run the Boston Marathon eight times and routinely gets six hours of sleep or less, waking at 4:05 a.m. on weekdays in order to train.

“Because I’m leading a very active and healthy life, I don’t expect to drop dead from a stroke,” said Wolfe, who is tall and thin, with a BMI of about 21.  

But there’s no question, adults function best with more sleep than six hours a night, experts say. Chronic sleep deprivation caused by getting too little most nights may boost the risk of stroke because it causes changes in the autonomic functions of the body, including blood pressure, heart rate, inflammation and glucose levels, said Dr. Phyllis C. Zee, associate director for Sleep & Circadian Biology at the Northwestern University School of Medicine.

“It not only affects the blood vessels to the heart and body, but also to the brain,” said Zee, who was not involved in the study presented at the meeting of the Associated Professional Sleep Societies.

It will take more research to determine whether short sleep actually results in more full-blown strokes for the REGARDS participants. But in the meantime, Ruiter said the study offers cautions for Wolfe and other middle-aged people who maintain their weight but scrimp on sleep.

“The important thing now is just to have physicians and people be more aware that the amount and quality of sleep might be important for how they feel and the quality of their health,” she said.

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By MyHealthNewsDaily

Preventing heart disease is not as easy as brushing your teeth.

While numerous studies have linked gum disease with an increased risk of heart disease and stroke, there is no proof that bad gums actually cause heart disease or strokes, an American Heart Association committee said after reviewing 500 journal articles and studies.

Moreover, claims that dental treatment may prevent heart attack or stroke are unwarranted, the committee of doctors, dentists and infectious-disease researchers said in a statement.

"The message sent out by some in health care professions – that heart attack and stroke are directly linked to gum disease – can distort the facts, alarm patients and perhaps shift the focus of prevention away from well-known risk factors for these diseases," said committee member Dr. Peter Lockhart, a professor of oral medicine at the Carolinas Medical Center in Charlotte, N.C.

It is biologically plausible, the committee acknowledged, that oral bacteria infections could cause heart disease. Mouth bacteria can enter the bloodstream during dental procedures and tooth brushing.

However, gum disease and heart disease share many common risk factors, including cigarette smoking, age and diabetes, and these factors are more likely to explain why diseases of the blood vessels and mouth occur in tandem.

Studies that show a strong relationship between gum disease and heart disease have failed to account for these common factors, the committee said.

"Individuals who do not pay attention to the very powerful and well-proven risk factors like smoking, diabetes or high blood pressure may not pay close attention to their oral health, either," Lockhart said.

One study even found invasive dental procedures, which include some treatments for gum disease, could increase the risk of heart attack and stroke.

A large, long-term study would be needed to prove whether dental disease causes heart disease and stroke, Lockhart said. Such a study isn't likely to be done in the near future, and it's most important to let patients know "what we know now, and what we don't know," he added.

Good oral hygiene is still important for overall health, and some studies show treatment of gum disease reduces markers of inflammation in the body, the committee said.

The committee statement will be published in the journal Circulation. It was endorsed by the American Dental Association Council on Scientific Affairs and the World Heart Federation.

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By MyHealthNewsDaily staff

Drinking alcohol moderately may lower women's risk of stroke, according to a new 26-year study of 84,000 women.

Women who drank low amounts of alcohol — about half of a glass of wine per day, on average — were 17 percent less likely to have a stroke compared with women who drank no alcohol. Women who drank about a glass a day were 21 percent less likely to have a stroke than abstainers.  

Those who drank more alcohol showed no reduction in stroke risk, according to the study.

The data are consistent with current guidelines for women about drinking alcohol, which suggest there is a modest reduction in stroke risk for women who drink less than one drink per day, the researchers concluded.

The study showed an association, not a cause-and-effect link, and was limited in that it relied on the participants to report their own alcohol consumption.

The study was published on yesterday (March 8) in the journal Stroke.

Alcohol and stroke risk
In the study, researchers at Brigham and Women's Hospital in Boston looked at 84,000 women who, at the study's start, had no evidence of cardiovascular disease and were between 30 and 55 years old. The researchers used data collected as part of the Nurses' Health Study, a large study of women's health that began in 1976.

Over the study, there were 2,171 strokes. Most were ischemic strokes, which occur when blood flow to the brain is blocked, depriving the brain of oxygen.

Of the 25,000 women who drank no alcohol, 1,045 suffered a stroke. Among the 29,000 women who drank lightly, 552 had a stroke, and 341 of the 20,000 who drank moderately had a stroke, according to the study.

About 30 percent of women in the study reported that they never drank alcohol, and 35 percent reported drinking very little, for example, less than half of a glass of wine per day, on average. Thirty-seven percent drank moderately — about one glass of wine or beer, or a mixed drink daily.

Only 11 percent of women reported drinking more than the equivalent of one mixed drink per day on average, and the researchers noted the small number of heavy drinkers in the study prevented them from drawing definitive conclusions about stroke risk in this group.

In general, increasing alcohol consumption was linked with being more likely to smoke and have high blood pressure, but also with doing more physical activity and having a lower body mass index, according to the study.

How it works
There are several ways the link between drinking and stroke risk could be explained, the researchers said. Alcohol may have compounds that increase "good" cholesterol and prevent blood clots. Higher levels of alcohol intake may increase the risk of high blood pressure and atrial fibrillation, which are risk factors for stroke.

The results are inline with a previous study, which found a 20 to 30 percent lower risk of stroke among men and women who drank low amounts of alcohol, compared with people who didn't drink alcohol.

The researchers noted that people who abstain from alcohol should not start drinking, due to the dangers associated with it.

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Short-term exposure to air pollution -- just a day or a week in some cases -- may kick off a heart attack or stroke, scientists now say.

Two new studies reveal that the risk of heart attack or stroke can jump after high-pollution days, especially for people who already have predisposing health problems.

Up to a week of exposure to most major types of air pollution may be enough to trigger a heart attack, a new analysis published in the latest issue of the Journal of the American Medical Association finds. Heart attack risk went up by almost 5 percent with high carbon monoxide levels and almost 3 percent with higher levels of air particles for up to seven days.

The risk of stroke jumped 34 percent after 24 hours of exposure to moderate air pollution, according to a study published in the latest issue of the Archives of Internal Medicine.

The increase in stroke risk was greatest within 12 to 14 hours of exposure to fine particulate matter and was most strongly associated with pollution from traffic.

No one knows exactly how much pollution will trigger a heart attack or brain attack, but experts suggest that vulnerable people protect themselves by minimizing time spent breathing air contaminated with a heavy dose of fine particles.

“What we can say is that exposure to a high level of pollution is harmful to people at risk,” said Dr. Hazrije Mustafic, the lead author of the analysis that examined data for pollution and heart attack risk in 34 previous studies.

“They must avoid the most polluted places, like highways, for example,” said Mustafic, a cardiologist and a researcher in cardiovascular epidemiology at the University of Paris Descartes, INSERM Unit 970. “We do not know how long of an exposure causes an excess risk of heart attack, but the relationship is linear.”

In other words, Mustaficsaid, as exposure increases, both in terms of time and intensity, so does the risk of a heart attack.   

The best recourse for those with cardiovascular disease may be to keep a close eye on local pollution levels, experts say. And government agencies are making that easier and easier.  The Environmental Protection Agency, for example, has a downloadable app that provides information on local air quality.

While short-term exposures to pollution can’t explain every stroke or heart attack, they do have a significant impact, experts said.

In 2007, for instance, there were 184,000 hospitalizations for stroke in the Northeastern U.S., said Gregory Wellenius, lead author of a paper on stroke risk published in the latest issue of the Archives of Internal Medicine.

“We estimate that 6,000 of those stroke hospitalizations could have been prevented,” Wellenius said.

His research study is the first to look at how short-term exposure to pollution impacts stroke risk. And, even though he found an increased risk, Wellenius is hesitant to offer advice until other studies duplicate his findings.

“This is just one study,” said Wellenius, who performed the research at Harvard’s Beth Israel Deaconess Medical Center and is now an assistant professor of epidemiology at Brown University. “It was done in Boston, a city notable because it has relatively low pollution levels. The study should be replicated in other parts of the country.”

The researchers did find that even moderate amounts of pollution can cause harm, said Roger Peng, an associate professor of biostatistics at the Johns Hopkins School of Public Health.

“They found a pretty sizable effect on ischemic stroke for a range of people at a relatively low level – one that is well under the national air quality standards,” Peng said.

The study is underscoring the point that “there is no safe level,” of pollution Peng added.

The culprit in both studies is particulate matter, tiny bits of material and droplets, known as PM2.5s. The particles come from a variety of sources, including power plants, factories, trucks and cars.

“These are very small particles, about a 30^thof the diameter of a human hair, ” Peng explained.

Peng suggested that people concerned about air quality download from the AIRNow app from the EPA’s website. The app works on both Apple and Android phones and allows users to get pollutant and ozone levels for more than 400 cities across the nation.

On bad air days, people at risk for heart attack or stroke might want to be careful about exercising outside, Peng said.

Other researchers go even further.  

“If you have any kind of cardiovascular risk factor it might be prudent to avoid anything that could make you breath hard and bring more junk into your lungs,” said Patrick Kinney, a professor of environmental health sciences at the Mailman School of Public Health at Columbia University. “The trouble with some of these pollutants is that they can get inside, too.”

The two new studies extend what scientists had already learned about pollution and cardiovascular disease, Kinney said. Earlier research showed that long-term exposure to pollutants could lead to clogged arteries, just as smoking cigarettes can, Kinney said.

While people can try to limit their personal exposure to these tiny particles, the best approach would be to get pollution levels down, Kinney said.

“To me this suggests the need to push for cleaner air,” he added. “If all cars and trucks were electric powered you wouldn’t have to worry as much.”

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A small switch in your daily schedule could significantly cut your risk of heart attack and stroke, a new study finds.

Taking blood pressure medications at bedtime instead of in the morning reduces the risk of a heart attack and other cardiovascular problems by about two-thirds, Spanish researchers reported.

The new study adds to a growing body of research that suggests blood pressure medication is more effective when taken before going to sleep instead of upon awakening. But the researchers caution that no one should switch from morning to bedtime dosing without first consulting a doctor and having his or her blood pressure monitored over a 24-hour period.

It’s now well-accepted that heart attacks are more common in the morning than the evening, says Michael Smolensky of the biomedical engineering department at the University of Texas at Austin. Smolensky wasn’t a coauthor on the new report but has collaborated with the authors.

Less widely accepted is the notion that blood pressure varies over the course of the day, so one or two readings in the doctor’s office doesn’t tell the whole story, says Smolensky, co-editor of the journal Chronobiology International.

“Mother Nature had in mind that when we went to sleep at night our heart rate and blood pressure would decline” to give our cardiovascular system a rest, Smolensky says. But, he says, people with high blood pressure are less likely to experience that nightly dip, which puts them at a greater risk of complications.

In an email to msnbc.com, lead author Ramon Hermida described bedtime hypertension treatment as “the most effective, cost-free approach to obtain the goal of greater sleep blood pressure reduction.” Still, says Hermida, director of the bioengineering and chronobiology labs at the University of Vigo in Spain, “all patients should be evaluated individually…with ambulatory blood pressure monitoring.”

Monitoring patients’ blood pressure over a day or two is important, because taking medication at night might lower it too much, Smolensky says. That could lead to falls if they got up to go to the bathroom at night or even increase their risk of a stroke because they weren’t getting enough blood to the brain, he says.

Hermida’s new study randomly assigned 661 patients to take all of their prescribed high blood pressure medications upon awakening or to take at least one of them at bedtime. At the beginning of the study, all of them wore ambulatory blood pressure monitors for 48 hours. They were tracked for about 5 ½ years on average and had their blood pressure monitored for 48 hours straight at least once a year.

All of the patients had chronic kidney disease. They represented a subset of patients in a larger study of the timing of blood pressure treatment. That study overall found a similar reduction in risk as it did in the kidney disease patients alone.

“Ours is just the very first trial ever testing the influence on cardiovascular morbidity and mortality of awakening vs. bedtime hypertension treatment,” says Hermida, who published his latest findings in the Journal of the American Society of Nephrology. “Further studies will be needed to corroborate our findings.”