New risk markers discovered for cardiac infarction and stroke

Published 6 July 2009

Heart attack and stroke afflicts many in spite of them having few or no known risk factors such as high blood pressure, diabetes, changes in blood fat or smoking.
-Because of this it is important to be able to identify those at risk who would benefit from preventive treatment, says Olle Melander, docent at Lund University and chief physician at Akutcentrum, UMAS.

He is the main author of a new article in the prestigious American journal JAMA that describes both modern and completely new biological markers to predict future infarctions.

Preventive cardio-vascular therapy is based on prediction of the ten year risk of infarction but this is difficult in the group with average risk, which is approximately one fourth of the middle aged population.
-Yes, and this group is important. We often don’t know whether to give preventive treatment or not, says Olle Melander and tells about one of the most important findings described in the newly published article.

-In spite of a strong correlation between several of the new risk markers and future cardiovascular disease, which was independent of the previously known risk factors, the effect of adding the new markers made little difference to the total risk.
-But we used new statistical methods that change focus from purely statistical correlations to a clinically significant context and saw that by using the new markers we could move 15% of the group with average risk into other risk categories, most of them to a lower risk group, says Olle Melander and adds:

-This means that many people are being treated without due cause.
One of the new markers that most strongly correlated with future cardiac infarction was the hormone adrenomedullin.
-Already ten to twelve years before the infarction we could see that patients that would be afflicted by stroke had elevated levels of adrenomedullin.

Adrenomedullin has many functions, including regulation of the body’s salt-water balance and contraction of blood vessels. It was previously know that patients who have suffered from an infarction have elevated levels of adrenomedullin.
-But we didn’t know if it was the chicken or the egg; if the high levels increased the risk of infarction or if they were a result of the infarction itself. Now we know that they are early warning signs, says Olle Melander.

There were also other risk markers, reflecting changes in salt-water balance, vessel constriction, inflammation and kidney function, that were elevated in the blood years before the infarction occurred.
The newly published study, the largest of its kind so far, is based on a follow-up of more than 5000 middle aged participants in the Malmö diet and cancer population survey.

Ten years ago none of them had any cardiovascular disease and the new markers could be investigated by comparing biological markers in stored blood samples from those that later suffered from strokes or cardiovascular disease with those that remained healthy.
-Cardiovascular disease is the most common cause of death but if we could identify those at risk with higher precision and give preventive treatment, many infarctions could be prevented or at least postponed, says Olle Melander.

The mapping of the changes in hormone levels that precede an infarction will also provide the scientists with important information on the basic underlying processes. This could lead to new principles for therapy and prevention of cardiac infarction and stroke.

The article in the Journal of the American Medical Association: