2nd quarter 2005

Myocardial infarction

Genetic testing helps to identify high-risk patients

Certain features of coronary heart disease, which causes angina pectoris and leads to myocardial infarctions, are more inheritable than others. Narrowing of the coronary arteries is more likely to be inherited the wider the affected vessel and the more blood it transports (main stem and proximal segments close to the origin of the vessel). Narrowing of the coronary arteries in these locations is particularly dangerous for the patient, because the thickness of the vessel is correlated with the amount of harm caused: The larger the clogged artery, the larger the amount of heart muscle destroyed.

"Our findings have shown for the first time that genetic factors not only play a major role in the development of coronary heart disease but also have a significant influence on the type of manifestation and severity of the disease. We should make it a rule to look not only at the patient, but also at the patient's family. If a patient shows a specific pattern of coronary artery disease, e.g. severe stenosis of the main stem, the risk of the patient's relatives also suffering from the disease can be assessed quite reliably by means of simple screening exams. Most importantly, this makes it possible to react in time. You could call this family-based prevention", says Christian Hengstenberg, one of the authors of the study.

The study comprised patients who had experienced a myocardial infarction before the age of 60, and who had at least one sibling also suffering from severe coronary heart disease (882 siblings from 401 families). The authors analysed the extent to which various aspects of coronary heart disease can be attributed to genetic causes and subsequently calculated the degree of inheritability of each aspect.

High inheritability

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  Age at first manifestation
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  Narrowing of coronary arteries close to the origin of the affected vessel, particularly in the left main stem
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  Calcification of coronary arteries
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  Dilatations of coronary arteries

Low inheritability

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  Narrowing of smaller vessel segments
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  Pattern of coronary blood supply
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  Number of affected arteries

"As the next step, we must try to identify the genes responsible for the different patterns of manifestation of coronary heart disease", says Hengstenberg. "After all, what we want to do is find the genes which cause coronary heart disease. This is the purpose of our investigations. Our approach is to first find a better way to categorise the disease and, next, identify the genes responsible for it."

30 May 2005