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TUESDAY, June 10, 2003 (HealthDayNews) -- Researchers have discovered people with a condition called coronary endothelial dysfunction appear to be at an increased risk for stroke.
Coronary endothelial dysfunction (CED) is a condition in which the arteries feeding the heart fail to expand normally. The problem lies with the endothelium, a thin layer of cells that form the lining of all blood vessels and regulate blood flow. It is thought that endothelial dysfunction may be a precursor to atherosclerosis, or hardening of the arteries.
While interesting, the finding, which is reported in the June 10 issue of Circulation, is unlikely to lead to any immediate or major changes in how people are diagnosed or treated.
"It's not overwhelmingly earth-shattering, but it's a nice study," says Dr. Daniel Fisher, a cardiologist with New York University Medical Center. "We already knew that endothelial dysfunction was associated with coronary disease [including heart attacks] and we already knew that heart attacks were associated with stroke, but we didn't know that CED in the heart was related to stroke. We all suspected this overlap."
The objective of the article was to pinpoint the relationship between endothelial dysfunction and stroke. To that end, the study authors looked at medical records for 503 patients who had undergone testing for coronary CED. Of these, 39 percent had normal coronary endothelial function, while 61 percent had evidence of dysfunction.
The records revealed that patients with CED had had five times as many strokes or transient ischemic attacks (TIAs or "mini-strokes") than those with normally functioning endothelium. CED was the single strongest factor associated with stroke or TIA even after adjusting for other risk factors including age, diabetes, hypertension, smoking history and obesity.
"One thing that was surprising was that it was so independent of other risk factors that we think are associated with stroke, such as irregularity of heart rate and high blood pressure and age," says study author Dr. Amir Lerman, director of the Mayo Clinic Chest Pain and Coronary Physiology Clinic. "The fact that it was such a strong predictor was a surprising point and alarming."
This new information may eventually lead to new ways to identify patients at risk for stroke.
"We need to put more emphasis on identifying patients at early stages of the disease rather than wait till when they present with more symptoms and heart attacks and strokes," Lerman says. "The function of endothelial cells is not [currently] considered an early stage of the disease. The study showed that the presence of this dysfunction not only leads to heart events but is also associated with stroke."
However, the testing methods used in the study are not ones that could be used to routinely identify people at risk. "It's a very invasive procedure," Fisher says. "All procedures, including this one, have risks." This particular one involves inserting catheters, usually through the groin, so they can travel to the heart and look at those arteries. The patient is also injected with a contrast dye and medications to check the response of the vessels.
"We don't recommend this as a screening tool," Lerman says. "The technology for a screening tool probably should come out in the next few years."
Lerman and his colleagues are already trying to identify and validate tests that would do the job noninvasively, perhaps through fingertip blood vessels (the endothelium is present in all blood vessels). They're also researching therapies for the condition in a special clinic set up just for this purpose.
All that is in the future, however. "They're putting a couple of pieces together, but it doesn't dramatically change how we treat patients," Fisher says. "The study provides more evidence that if you have heart disease or are at risk for heart disease, you should also be concerned with stroke."