A blood test that measures white blood cell counts may provide a simple, cheap way to refine predictions of heart attacks or death, according to researchers at LDS Hospital.

Their study of 3,227 patients is being published in the Journal of the American College of Cardiology.

The study indicates that risk of heart attack or death was higher in patients with elevated total white blood cell counts. But an even better predictor was looking at two subtype white cell count measures, the ratio of neutrophils to lymphocytes, said Dr. Jeffrey L. Anderson, associate chief of cardiology at the hospital. Patients with the highest ratios, those in the top 25 percent, had more than double the risk of heart attack or death as patients with the lowest ratios.

With a top ratio of neutrophils to lymphocytes, the risk increases twofold, Anderson said, compared to a 40 percent increase in risk associated with total white blood cell count. And those with the highest level of lymphocytes had just half the risk of those with the lowest lymphocyte levels. It's a case of more is better.

Neutrophils are a subtype of white blood cells that form a primary defense against bacterial infections. Lymphocytes are a subtype that identify foreign substances and germs, both viral and bacterial, and produce antibodies.

Scientists worldwide now widely believe that inflammation in blood vessel walls is significant to development of atherosclerosis — hardening of the arteries — which leads to heart attacks and strokes. Several new blood tests have been developed to help identify that inflammation, including measuring C-reactive protein.

Most of the new tests are quite expensive, Anderson said. Complete blood panels are relatively inexpensive and are commonly done for many reasons. If the results of this study are confirmed by other studies, it could have a significant impact. "Even without increasing the cost at all, we found a useful additional predictor."

He believes a calculation can be developed using this and other factors that would help quantify risk and drive some treatment/prevention decisions. They could indicate who needs more aggressive treatments or prevention.

The white cell count ratio seems "as predictive" of heart attack and death (from heart attacks and other causes) as many risk factors that are now looked at routinely, he said.

But it's just one more piece in an increasingly complex puzzle that includes risk factors like high cholesterol, high blood pressure, diabetes, aging and lifestyle factors like smoking.

The researchers looked at blood test results from patients who had undergone coronary angiography at the hospital between 1994 and 2001. They did not show signs of having suffered a heart attack immediately before the angiography, and the records followed them for a period averaging 3 1/2 years. The patients are part of what has become the heart collaborative study, which has yielded a number of findings related to heart disease.

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