A simple procedure with greatly reduced risks has meant a significant reduction in bypass surgery, writes Fiona Tyrrell
Major advances in treatment options for those at risk of a serious heart attack have resulted in reduced waiting times for bypass surgery and significant improvement in outcomes.
Coronary heart disease is the number one killer in Ireland and in 2004, 24 per cent of all deaths in Ireland were as a result of diseases of the circulatory system.
While there are no figures for the prevalence of the disease in Ireland, the number of patients discharged from Irish hospitals with a diagnosis of coronary heart disease rose from 21,651 in 1999 to 25,335 in 2003.
This increase reflects a number of facts, according to Dr Brian Maurer, director of the Irish Heart Foundation and consultant cardiologist at St Vincent's Hospital and the Blackrock Clinic.
It is a result of better access to services that, in turn, is a result of the number of newly appointed cardiologists. It also reflects an improved survival rate in those admitted, he says, thanks to the success of preventative measures and improved treatments - drugs, surgery and stenting.
Traditionally, those at risk of heart attack underwent a bypass operation involving the use of a piece of vein or artery to bypass a blockage in the coronary arteries (blood vessels), which carry blood and oxygen to the heart muscle.
In recent years there has been a significant reduction in the number of traditional heart bypass operations in Ireland because of major developments in stenting, which is a simple procedure with greatly reduced risks.
Coronary stenting is usually a one to two-hour procedure. It is commonly undertaken following a balloon angioplasty, where a balloon catheter is inserted into an artery via the groin and inflated to widen a coronary artery that has become blocked.
A stent is then threaded into the artery and placed around the deflated balloon. When the balloon is inflated it expands the stent against the walls of the coronary artery and once the balloon catheter is removed, the stent is left in place to hold the coronary artery open.
The concept of the stent grew out of interventional cardiologists' experience with angioplasty balloons in the late 1970s and early 1980s, which were used to treat narrowed or blocked coronary arteries. Sometimes the wall of the coronary artery became weakened after balloon dilatation or the arteries began to close up again.
Although the rates were somewhat lower, bare metal stents treatment still resulted in reblocking of the artery (restenosis). The development of scar tissue building up in the stent, causing a blockage, occurred in about 25 per cent of cases, necessitating a repeat procedure.
Although stents were first used in Ireland 12 years ago, it is the new generations of stents, drug-eluting stents, licensed in Ireland in the past three years, which have revolutionised the treatment of people with coronary heart disease. The drug-eluting stent promised to solve one of the biggest problems of interventional coronary treatment - restenosis.
A drug-eluting stent is a normal metal stent that has been coated with a drug that is known to interfere with the process of restenosis.
Re-blocking of the artery occurs in only about 4 or 5 per cent of cases after the use of drug-eluting stents, compared with the 25 per cent of patients treated with bare metal stents. Describing drug-eluting stents as the "big revolution" in treatment, Dr Maurer says the emergence of this new treatment has led to a significant shift away from bypass surgery.
"It is a major revolution not only in terms of the number of patients who benefit from stenting but the number of arteries that can be treated. Five years ago, the only option for a patient with two, three or four narrowed arteries would have been surgery," he says.
More than 10,000 angiograms were carried out in Irish public hospitals in 2004 and an estimated 3,000 were conducted in private hospitals. Following on from that around 5,500 patients underwent a stenting procedure. Only 1,437 underwent surgery, down from 1,810 in 2003, according to data from the Hospital In Patient Enquiry Scheme (Hipe).
The 2004 Central Statistics Office's figures indicate that the death rate from cardiovascular disease is falling fairly dramatically, down from 12,000 in 2001 to 8,800 in 2004, Dr Maurer says.
Although some of this can be attributed to better preventative strategies, much of it can be attributed to better treatments, he says.
The risks associated with stenting include a very small and immediate risk of death and a 1 per cent risk of serious complications. The fact that a stent is an artificial substance in the artery means that drugs will have to be taken to prevent clotting. So, in addition to taking Aspirin, which anyone with the disease is advised to take, patients are advised to take extra anti-clotting drugs to prevent in-stent clotting for one year following the insertion of the stent.
The downside, however, to blood-thinning drugs is that they can increase the risks associated with general surgery. They do not increase the risks associated with coronary artery surgery.
There are still risks associated with stenting and these will depend on how seriously ill the patient is, according to Dr Maurer. However, the mortality rate for the procedure is not more than 0.3 per cent, compared with a 2.5-3 per cent risk associated with coronary surgery.
Multiple stenting is a longer and riskier procedure and sometimes surgery is preferable, according to Dr Maurer.
Stenting doesn't cure the disease, it just improves the supply of blood to the heart, he warns.
Anyone who has had a stent procedure must still combat the ongoing disease in the rest of their arteries and must take the same treatment measures as everybody else with the disease.
With the shift away from bypass surgery, waiting lists for surgery have also significantly reduced. From a high of up to three years, there is no longer a significant waiting time for cardiac surgery, according to intervention cardiologist at Beaumont Hospital, Prof David Foley.
He describes stent development as a "breakthrough technology" that is a great example of how emerging technology can revolutionise treatment.
There are a number of stents on the market. Johnson & Johnson's device is called the Cypher, Boston Scientific's is called Taxus and Medtronic's is Endeavor.
A new kid on the block which is "a very interesting alternative", according to Prof Foley, is the Genous stent. This is an antibody-coated stent that accelerates the natural healing process and encourages the growth of a layer over the stent, providing protection against thrombus and minimising restenosis.
The high-level competition between different device manufacturers, marked by legal disputes and a plethora of clinical trials claiming to show superiority of one device over another, has led some commentators to coin the phrase "stent wars".
"It's fair to say that every individual surgeon will have a preferred product and sometimes it depends on the nature of the artery," Dr Maurer says.
But for the patient, advancement of stent technology means less invasive treatments and shorter recovery times.
Stenting can be done on the basis of a 24-hour admission to hospital, the patient doesn't have a big scar on their leg, chest or arm and once out of hospital they are back on their feet within a few days. Bypass surgery involves a seven to 10-day stay in hospital and a recovery time of four-six weeks.
The fact that a stent is an artificial substance means that drugs will have to be taken to prevent clotting