Cardiovascular disease risk and genetic testing

Cardiovascular disease affects millions of people worldwide, accounting for 30 percent of global deaths in 2008 according to the World Health Organization (WHO), most due to coronary artery disease and stroke. According to the Centers for Disease Control, heart disease, particularly coronary artery disease, is the leading cause of death in the United States.

The WHO recognizes six ‘types’ of cardiovascular disease, or CVD, that affect the heart and blood vessels:

  • coronary heart disease (or coronary artery disease)
  • cerebrovascular disease – associated with strokes
  • peripheral arterial disease
  • rheumatic heart disease – associated with infection of the heart
  • congenital heart disease
  • deep vein thrombosis and pulmonary embolism

Hypertension is sometimes considered a cardiovascular disease and is recognized as a risk factor for heart disease. Heart disease tends to run in families, indicating the role of genetics in its course.

Coronary artery disease is caused by atherosclerosis, which often develops in the presence of excess blood cholesterol levels. Coronary artery disease can cause heart attack and chest pain (angina pectoris) due to decreased blood supply to the heart muscle. In 2009, USNews reported on the groundwork being laid for a genetics test to determine a person’s susceptibility for heart attack. Several research studies had identified more than a dozen genetic variants that increase a person’s risk of heart attack, some via effects on cholesterol. The genetic tests could indicate a person’s potential for developing the disease genetically and help pinpoint the best treatment options.

That same year a genomics company in Iceland, Decode Genetics, launched a genetic test that detects eight single nucleotide polymorphisms associated with heart attack and various blood vessel disorders. However, the test was criticized for not being highly specific for actual disease risk, something that has yet to be overcome.

Due to the vast number of variants involved in the different cardiovascular diseases some patients opt for genome-wide analysis. This is much more expensive (costing tens of thousands of dollars), but could potentially indicate preventative treatment. The Wall Street Journal in early 2010 discussed the case of an engineer whose genome-wide results prompted his doctor to put him on pharmaceutical therapy for heart disease he did not yet have, or may never have. This raises the question of whether the small possibility of actually developing the disease is worth the trade off for drug side effects, which can sometimes be severe or lethal.

However exciting it may be to know what genetics has in store for your body, environmental factors are much better predictors, and more easily controlled factors, of the development of heart disease. Poor diet, lack of exercise, smoking and stress can still cause disease in people with ‘good’ genetics – so what would a genetic test for cardiovascular disease risk be good for?

A better use of genetic testing for cardiovascular disease was highlighted in USAToday in October 2010. In individuals with chronic chest pain a genetic test could help doctors determine who requires an angiogram – a diagnostic procedure used to visualize the flow of blood in the coronary arteries via catheterization and X-ray imaging. Avoiding the procedure in those who are not suffering from coronary artery disease can increase clinical efficiency and diagnosis while reducing health care costs. The test looks at the activity of 23 different genes to determine whether a person currently has heart disease, which would then lead to an angiogram to plan appropriate treatment.

Though there is not, and likely will not be, a magic test to determine whether you may one day have a stroke or heart attack, genetic testing is being developed and used to help determine the best course of treatment in people with risk factors for heart disease or established heart disease – reducing side effects and increasing quality of life.