How is the resorption of the stent in the body monitored?
Napp: We do not regularly monitor the healing or release of the drug, as this cannot be checked using a single method. However, for patients with constrictions in all three coronary arteries, treatment is carried out step by step. These constrictions should not be treated all at once, not even with metal stents. If the patient had to undergo surgery in this condition due to an accident, the antiplatelet drugs would have to be discontinued. This could lead to stent thrombosis, which can occur in all three vessels at the same time and is life-threatening.
This is why we treat the vessels one after the other in cases of severe coronary heart disease. When treating the second vessel, which takes place around two months after treatment of the first vessel, we can use the fiber optic camera to check how the stent has dissolved in the vessel that has already been treated.
Are there any risks or complications that can arise from the degradation process of the stents?
Napp: The idea of producing self-dissolving stents has been around for more than 30 years. The magnesium stents that we are now using have also been around for a while and have been continuously developed further. There are other materials from which self-dissolving stents are made, such as lactic acid or special plastics.
However, lactic acid products, also known as polylactides, have led to an increased number of complications in studies, which has had a negative impact on the overall perception of self-dissolving stents. Even magnesium stents, which did not have these problems at all, were also perceived negatively due to press reports about complications with self-dissolving stents. This was unjustified, as this is a completely different design.
Although there are risks and complications that can occur with self-dissolving stents, this depends heavily on the material. This does not typically apply to magnesium. Magnesium is an endogenous substance that is broken down into calcium acetate. This calcium acetate is an amorphous mass that remains in the vessel wall, where it does not cause any problems.