"To the best of our knowledge, this study is the first to indicate that high triglycerides expose heart disease patients to increased risk for stroke beyond cholesterol," says a statement by Dr. David Tanne, director of the stroke unit at Sheba Medical Center in Tel Hashomer, Israel, and lead author of a paper reporting the finding in the Dec. 11 issue of Circulation: Journal of the American Heart Association.
Triglycerides, like cholesterol, are in the family of fats, or lipids. Cholesterol is a building block for cells, while triglycerides contain fatty acids that are metabolized for energy. Although high blood levels of LDL cholesterol, which causes fatty deposits to build in the arteries, have long been identified as a risk factor for heart attacks and stroke, it is only recently that studies have shown high triglyceride levels to be an independent risk factor.Last year, for example, University of Washington researchers said a long-running family study showed that high triglyceride levels increase the risk of death from heart disease. And the link has been confirmed by the long-running Framingham Heart Study.
The Israeli researchers followed more than 11,000 patients with coronary heart disease who had no previous history of stroke or transient ischemic attacks (TIA), which are temporary cutoffs of blood flow that cause stroke-like symptoms but no lasting damage.
Over six to eight years, 941 participants had either TIAs or ischemic strokes, the kind caused by blockage of a blood artery. Those patients had higher than average levels of triglycerides, the report says.
"Those with high blood triglycerides, over 200 milligrams per deciliter, have a nearly 30 percent higher risk of suffering a stroke, after taking into account other risk factor[s] for stroke, such as high blood pressure, cigarette smoking or diabetes," Tanne says.
But the risk of stroke is reduced by high blood levels of HDL cholesterol, the "good" kind that carries fat away to be metabolized, the study finds. The fatty particles associated with triglycerides are believed to form the deposits that eventually block arteries, causing heart attacks and stroke, the researchers say.
"This is something I would have anticipated, but it's nice to have documentation," says Dr. William Connor, professor of medicine and clinical nutrition at the Oregon Health Sciences University. "We have thought that triglycerides and low HDL cholesterol are implicated in all diseases affecting the arteries. This is fascinating for people who are susceptible to stroke."
From a doctor's point of view, the new findings about blood triglyceride levels indicate the need for special measures to counsel patients, says Dr. Richard Stein, a spokesman for the American Heart Association.
The statin drugs that are highly effective in reducing blood cholesterol levels are not that good at lowering triglyceride levels, Stein says. Niacin can do the job, he says, but it can cause potentially dangerous changes in liver enzymes.
So diet becomes more important for people with high triglyceride levels, Stein, chief of cardiology at the Brooklyn Medical Center, adds.
Fibrate drugs such as gemfibrozil can help keep triglycerides under control, Connor says, but the standing recommendations about regular physical activity and proper diet are always important.
"Diet is the most important thing," he says. "A low-fat, high-carbohydrate diet is effective. Fats can come from fish, which have omega fatty acids that lower triglyceride levels."
"This really calls into play the need for the physician to spend time with patients going over modifications of diet," Stein says. "You can't just hand a patient a list and say, 'This is what you should eat.' This requires more attention to dietary counseling than physicians have used until now."
What To Do
The link between triglyceride levels and risk of stroke reinforces the American Heart Association's standard recommendation for reducing fat intake, Stein says. But many people make up those calories by increasing their intake of sugary foods, which actually can increase blood triglyceride levels, he says. The better way is a greater intake of fruits and vegetables, which contain complex carbohydrates.