The Problem With Angioplasty
ATTENTION: PATIENTS WITH CORONARY ARTERY DISEASE
The Problem with Angioplasty
Coronary artery disease is the number one lethal disease in the United States. It kills more men and women in this country than all forms of cancer combined. The most common intervention for coronary artery disease is Angioplasty. The alternative is coronary bypass graft surgery.
This article is an explanation of the limitations and failures of Angioplasty.
THE PROCEDURE AND ITS HISTORY:
During Angioplasty a polyethylene catheter or tube (2 to 3 millimeters in diameter) is threaded up from the femoral artery at the top of the thigh to the heart. Using fluoroscopic visualization (a real time continuous x-ray) the catheter is directed into the coronary arteries. The catheter has a balloon near its tip, which is placed in the narrowed part of the coronary artery. The balloon is expanded in an attempt to widen or destroy the plaque that narrows the coronary artery.
Introduced in the 1980’s, Angioplasty rapidly became commonplace. The procedure was initially limited to coronary artery disease involving one or two of the three coronary arteries. However, the procedure now is used by Cardiologists in even the most severe cases of coronary artery disease.
Often after Angioplasty, the narrowed area of the coronary artery shuts down again within hours, days or months. As a result, the procedure has been augmented to include stents, small wire or polyethylene mesh structures placed over the area of previous narrowing, to keep the artery from closing down by clots or scar tissue.
THE BIOLOGY:
The wall of the coronary artery is composed of three layers: the internal lining (the Endothelium), the middle layer (the Media) and the outer wall (the Adventicia). The narrowing material, the cholesterol-calcium plaque, lies in the middle of the artery wall, the Media. The plaque is covered by the Endothelium. The Endothelium is the only material which blood can touch without clotting.
Normally clotting does not cause increased narrowing of the coronary arteries. Increased narrowing of the artery occurs by one of two mechanisms. 1) There is growth of the plaque material. 2) A small artery within the plaque bursts causing sudden severe narrowing or occlusion of the coronary artery. The latter is the most common cause of sudden death.
THE RISKS:
The Angioplasty procedure flies in the face of the biology of arteries and their interaction with blood.
During Angioplasty, in order to alter or destroy the plaque and relieve the narrowing, the balloon on the catheter has to tear or injure the Endothelium. Tearing the Endothelium exposes the Media to blood flow. The Media, unlike the Endothelium, is not clot resistant. With the injury to the Endothelium, a clot begins to form on the exposed Media and can progress to full closure of the artery. The only reason the procedure does not always result in clotting off the artery is that the blood flow washes away clot build up. However, sometimes the clot formation can be persistent enough to clot off the vessel.
A separate risk can result from the balloon tearing the endothelial wall. The tear is enlarged by normal blood flow down the artery creating a “flap” which closes off the artery. Either one of these two of these events is potentially lethal and can create a surgical emergency.
An additional risk occurs when the balloon destroys the plaque and a spray of the plaque material is blasted down the artery. Usually the sprayed material is only in small particles that occlude the smallest of coronary arteries, which supply only a small portion of cardiac muscle. That small amount of cardiac muscle is also supplied by surrounding vessels. There is, in this case, no heart attack. But sometimes the particles are in fact large enough to occlude larger vessels and cause irreversible damage to some of the heart muscle. If surgery eventually becomes necessary this permanent damage to the heart muscle significantly elevates the lethal risk of surgery.
Sometimes the patient is lucky and the build up of new plaque and scar tissue takes months. However, the artery is never normal again.
THE DOWNSIDE OF STENTS:
The introduction of stents has improved but not eliminated arterial closing problems. Some stents actually increased the problem of artery closure. Those stents have been removed from the market, but every new stent design carries a potential risk of increased arterial closure.
Some stented arteries appear to be successful; however, in the long run (around one year or more), approximately 50% of patients have a re-hospitalization for recurrence of cardiac symptoms. It is difficult to put an exact number on re-hospitalization events since studies from different institutions have reported widely varying results. Suffice it to say, the American College of Cardiology has recommended that patients where all three major coronary arteries have significant disease should not have Angioplasty with or without stents.
THE OPTIONS FOR PATIENTS:
If you are a patient with coronary artery disease, I doubt if your Cardiologist has explained the process of Angioplasty as completely as I have in the above paragraphs. So what does he say? Often his first remark will be something like, “I think we can solve this problem without surgery!" That statement is welcomed with enthusiasm from the patient who often fears invasive surgery.
The Cardiologist may or may not explain the problems of recurrent narrowing, or acute closure, or that the mortality with the Angioplasty procedure is the same as a complete surgical correction. (Depending on the skills of the surgical team he uses). Or has he mentioned the possibility of permanent cardiac muscle damage that may occur and give a subsequent surgical procedure a higher mortality rate? Probably not. You see, one of the main problems is that with an Angioplasty the Cardiologist most often is referring himself – he will do the Angioplasty. Or, if he does not, he will refer you to another Cardiologist who does such procedures. No surgeon is involved in this decision or process. Ask your Cardiologist for a Cardiac Surgical consult.
Surgery may be less risky in your case than Angioplasty. Consider some high profile patients such as David Letterman or President Clinton who had coronary artery bypass and not Angioplasty. In these high profile instances, a Cardiologist would not want re-hospitalization because of symptoms, or certainly not a cardiac death on his resume.
Angioplasty can work, but it may take multiple hospitalizations and repeat procedures. Each repeated procedure carries new exposure to risks, especially heart muscle damage, which may limit the benefits of future bypass graft surgery and even increase the risk of that surgery.
In my opinion Angioplasty is overused. The flaws of the procedure and its potential dangers should be emphasized to the patient.
In future articles, I will discuss the risks of emergency surgery versus the advantages of elective coronary bypass graft surgery…