An almost universal and highly relevant question is asked over and over again after a dilation procedure in an artery of the heart is: "How long is it good for?"
Somewhere in the answer to this question, you will hear the term "restenosis" and you will want to know more about it.
What is restenosis
In fact, by definition, restenosis is a recurrence of narrowing, from the stenosis of the artery to the site of dilatation. It is therefore the loss of the initial benefit obtained by the intervention.
Two main mechanisms are involved in restenosis.
• Elastic property of the artery
• The process of repairing the artery (Healing of the wound)
Elastic property of the artery
The first mechanism depends on the elastic properties of the artery.
A significant portion of the gain inside the artery during dilatation results from the stretching of the wall, in other words, its outward movement. The artery, far from being a rigid conduct, is indeed relatively flexible and can be stretched. This flexibility, or compliance, can vary due to various factors, including fibrosis and the amount of calcium present in the artery wall.
A lack of compliance can greatly limit the possibility of obtaining an adequate result.
The artery is surrounded by an elastic layer, called the media, which exerts a reverse force and tends to return the artery to its initial configuration in the first hours and days after dilatation.
To illustrate the phenomenon, professionals use the term «recoil».
In the early years of dilatation, when only balloons were used, it quickly became clear that this mechanism was a major source of failure in the short and medium terms, with consequent recurrences of angina.
The arrival of coronary stents, which provide a framework within the artery, has almost eliminated this mechanism of restenosis.
The process of repairing the artery (Healing of the wound)
The second mechanism puts more at stake the process of healing the wound of the artery.
Without being too simplistic, the dilation of the artery imposes a trauma and as for any injury, a healing process will take place.
This process of healing involves a proliferation (multiplication) of different cellular elements present in the wall of the artery. In some cases, the scar may "grow" through the mesh of the stent and reduce the diameter of the artery once again and cause a recurrence of symptoms.
Controlling the healing of the artery
For many years, researchers have tried various strategies to hinder this excessive healing. It was necessary to find the difficult balance between too much scarring or incomplete healing, opening the door to other complications.
The research finally led to the development of a new generation of "medicated" stents. They are indeed covered by a medication that is released and is gradually diffused during the first months after the implantation in the wall of the artery to reduce the importance of healing. This breakthrough has revolutionized angioplasty by dramatically reducing the risk of restenosis. This risk is never zero, however.
How long is it good for?
Then, to the question: "How long is it good for?” ... There is unfortunately no precise answer ... Here we are confronted with the complex domain of probabilities.
Factors to consider
Some factors are known to increase the risk of restenosis.
A narrowing on a long segment of a small diameter artery is clearly at greater risk for recurrence. These are characteristics, among others, that we find more in women and diabetic patients.
A suboptimal result of the dilation due to calcifications or the presence of a narrowing in a bifurcation site, or in other words at the exiting point of an artery branch, are other elements promoting restenosis.
In assessing the risk of recurrent angina after dilatation, one must of course also consider the number of cases that have been treated. Indeed, each lesion taken individually has its own risk of restenosis that adds to that of others.
What is the best treatment option?
During coronary angiography, the physician will consider all of these factors to advise the patient of the best treatment option. In some cases, where the risk of restenosis, or the consequence of it, is too great, the best option may be to consider bypass surgery.
The patient's expectations and preferences must of course be explored and have an important place in the final choice of treatment.
How is restenosis treated?
First, it is very rare to find a restenosis that does not cause any symptoms by repeating a coronarography or another imaging procedure. This may rarely be the case during dilatation at critical locations where the consequences of restenosis can be severe.
In general, the follow-up will be done mainly according to the recurrence or not of symptoms.
The first 3 to 6 months
During restenosis, angina recurrence will usually occur within 3 to 6 months after the initial procedure.
If this is the case, chest pains usually reappear during significant efforts at first, but gradually appear during smaller efforts and eventually may even happen at rest.
Angina that reappears
Restenosis is very rarely in the sudden form of a stroke; the symptoms occur rather gradually.
Angina is usually quickly recognized by the patient.
In patients who do not feel chest pain, the equivalent will be a marked shortness of breath in the effort.
The return to coronarography
Most of the time, the doctor will suggest a coronarography follow-up that will determine what happens next.
Obviously, a treadmill control or other examination may be required prior to the coronary angiography follow-up.
What are the options for confirmed restenosis?
Once restenosis has been demonstrated, the stent previously placed cannot be removed.
A new dilatation is however possible inside, sometimes even with the deployment of a new stent. Rarely, some patients may have multiple procedures at the same site. It should be known that the risk of restenosis is always greater with each recurrence.
In some cases, depending on the location of restenosis, or multiple recurrences, it may be that bridging surgery may become the preferred option.
In conclusion, although restenosis has become much rarer, it is still a challenge in the treatment of dilation of coronary narrowing. It must still be considered in the choice of treatment, as well as the expectations of the patient.
It always reminds us that despite all our efforts, the coronary heart disease is controlled, but cannot be cured ...