Arteriosclerosis is the most common disease of the arteries worldwide. It is estimated that around four million people in Germany alone suffer from it. One form of arteriosclerosis is atherosclerosis, which has a very similar name. The deposits in the arteries that occur usually develop gradually. Those affected often remain free of symptoms for decades – until a blood vessel becomes so narrowed or blocked that a heart attack or stroke is threatened.
There are many causes for the dangerous deposits. The biggest risk factors are:
- High blood pressure
- Obesity
- high blood fat levels (cholesterol levels)
- Diabetes
In addition, an unhealthy diet, lack of exercise, stress, smoking and alcohol can encourage deposits. Genes also play a role.
Previously unknown risk factor for atherosclerosis
Researchers from Spain have now investigated another risk factor for atherosclerosis: mutations in the blood cells. In the professional world, these are called colonic hematopoiesis. Their abbreviation “CHIP” is derived from the first letters of their English name: c lonal h ematopoiesis of i ndeterminate p otential. The mutated blood cells are also called blood cell clones.
The likelihood of such mutations increases with age. But younger people can also develop CHIP. Scientists have been targeting CHIP mutations for some time. There are now a large number of studies linking CHIP to cardiovascular diseases. However, they are still hardly known among the population and have not yet played a major role in the prevention of heart attacks and strokes.
3700 people examined over six years
The current study from Spain confirms that CHIP promotes atherosclerosis. It was published in the journal “Nature Medicine”. The researchers examined around 3,700 men and women who were between 40 and 55 years old at the start. They followed the subjects for a total of six years. During this period, they took blood samples at three points in time and examined the femoral arteries of the study participants for deposits.
The researchers discovered two things:
- If a person has CHIP mutations, his risk of developing atherosclerosis in the thigh within the next three years is 2.1 times higher than in people who do not have these mutations.
- There have more people have CHIP mutations than previously thought – about six percent of all middle-aged people.
The study shows for the first time the influence of CHIP on vascular deposits in human arteries over time, says Stefanie Dimmeler, director of the Institute for Cardiovascular Regeneration in Frankfurt am Main. And it also takes particularly small blood cell clones into account. This has only rarely been done in previous studies, so many mutations remain undiscovered.
However, Dimmeler criticizes the fact that the researchers only examined the thigh and not deposits in the area of the heart.
The research team was unable to detect an increase in CHIP in people who already had atherosclerosis. This is an important finding for understanding whether the mutations cause the disease or whether the disease causes the mutations. From this, the researchers now conclude that CHIP causes atherosclerosis, but that the disease is not the cause of the mutations. This contradicts other studies that assume a vicious circle.
Early screening could prevent heart attacks
“We know that the currently known ‘classic’ risk factors such as hypercholesterolemia or high blood pressure are only responsible for about 50 percent of the cases of atherosclerosis that arise,” explains Dimmeler. “CHIP could be one of the previously unknown additional ‘unmodifiable’ risk factors and play an important role in prevention.”
There are already centers where patients are tested for CHIP mutations, including in Munich and Frankfurt. However, the costs for this are currently still very high. “However, cheaper alternatives are already being developed that should cost less than 100 euros,” says Dimmeler.
Every third heart patient has CHIP
Cardiologist Moritz von Scheidt also stresses how important it is to detect CHIP early. One in three patients who already suffer from coronary heart disease is affected by CHIP. If detected early, appropriate measures could effectively prevent a heart attack or stroke. It would be conceivable to introduce targeted measures for those affected to eliminate other risk factors: for example, stopping smoking, abstaining from alcohol or encouraging more exercise. But medications with an anti-inflammatory effect could also be used for them.
“It would be practical to carry out screening in high-risk population groups, particularly in older patients or those with previous cardiovascular diseases,” says von Scheidt. This includes, for example, patients aged 50 and over who have already been diagnosed with atherosclerosis, or patients aged 60 and over who have more than one risk factor – such as high blood pressure and diabetes. Von Scheidt heads the special Clonal Hematopoiesis (CHIP) consultation at the German Heart Center in Munich.
