Technical advances cut risks in fight against heart disease

The treatment of coronary artery disease, our biggest killer, is becoming a relatively simple procedure with greatly reduced …

The treatment of coronary artery disease, our biggest killer, is becoming a relatively simple procedure with greatly reduced risks. Sarah Conroy reports

Heart disease and stroke is the number-one killer of Irish people resulting in 11,000 or 43 per cent of deaths in Ireland per annum. The development of drug-eluting (medicated) stents has been a major advance in the treatment of this disease and has reduced the number of patients requiring cardiac surgery.

Coronary artery disease occurs when the coronary arteries (blood vessels), which carry blood and oxygen to the heart muscle, become clogged with plaque. This plaque contains cholesterol and cells that form around the lining of the artery. When the plaque is large it limits the blood supply leading to chest pain called angina. If a blood clot forms over the obstruction, there is a sudden reduction in blood flow, which results in a heart attack.

Traditionally, severe coronary artery disease has been treated with open-heart surgery. However, there has been a decline in the number of bypasses carried out each year. Surgeons who carry out bypass operations and consultant cardiologists who perform angioplasty procedures both have noticed this trend. "There is a big decline in people having bypasses. The number of stenting procedures has overtaken it by a long shot, there are much fewer people having bypasses now," says Michael Tolan, cardio-thoracic surgeon at St James's Hospital, St Vincent's Hospital and the Blackrock Clinic.

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A bypass procedure involves the patient undergoing a two- to three-hour operation, making an incision over the middle of the chest and using a piece of vein or artery to bypass the blockage. "With bypass you are putting in new pipes and leaving the old ones," says Tolan.

Coronary artery bypass is one of the most commonly performed operations in the world. Typically after surgery, a patient spends approximately six to seven days in hospital and six to eight weeks recuperating. Long-term medication involving a blood-thinning drug such as Aspirin is required to prevent stroke or blood clotting.

This operation is very successful. "Some 94 per cent of graft arteries will still be open at 10 and up to 20 years, as they do not deteriorate. However, using veins to bypass a blockage is not as good, half of the veins are blocked at 10 years and the other half have significant obstruction. That is why we use as many arteries as grafts as possible," says Tolan.

However, with the licensing of drug-eluting stents in Ireland in the past two years, cardiologists now have the opportunity to carry out more complex procedures without recourse to surgery.

"Cardiologists are more willing to take on procedures they wouldn't normally have, skill levels have changed and so they are willing to take on diseases that used to be in the realm of the surgeon," says Dr Martin Quinn, consultant cardiologist at St Vincent's Hospital and the Blackrock Clinic.

Angioplasty with stenting is approximately a one-hour procedure whereby a small catheter is fed into a blood vessel in the groin or wrist. "We put a little wire in through the catheters, we then put a little balloon over the wire so as to direct the balloon and our specialised equipment down to the centre of the blood vessel. The stent is a small metal support structure, which is crushed down on the balloon. We blow the balloon up to deliver the stent [ to open the blockage] and then deflate it, the balloon is removed and the stent stays in," says Quinn. Stents vary in size from 2.5mm to 4mm depending on the size of the target arteries.

The benefit of angioplasty over bypass is that it is a far less traumatic procedure with only an overnight stay and full recovery within a couple of days.

Previously one in six people would develop restenosis, whereby after putting a (non-coated) stent in, scar tissue would gradually build up in the stent, causing a blockage to reoccur. Drug-eluting stents are coated in a medication that significantly reduces the risk of restenosis. With these stents the risk of restenosis in the same spot is very low, affecting approximately one in 30 patients, according to Quinn.

The risks associated with angioplasty are minimal. "The risk of an adverse event among stable patients is one in 200, the risk of stroke one in 500 and the risk of heart attack one in 200," says Quinn.

Patients are required to take drugs such as Aspirin, medication to lower cholesterol and other risk factors such as blood pressure and a healthy diet must be continuously modified.

Tolan agrees: "The severity of coronary artery disease is a continuum; it varies from minor disease which may cause mild angina and is best treated with a medication, to a one to two vessel disease which is usually best treated with stenting, to a more severe disease with complex obstructions especially in diabetics. These are most often best treated with surgery.

"The advent of drug-eluting stents is fantastic for patients and shows excellent early promise and allows cardiologists to treat more severe diseases. However, surgery is still necessary in some patients and, to most, a week in hospital and six weeks' recuperation is a good trade-off for a procedure offering an excellent prospect of long-term relief of symptoms and gain in life expectancy. Sure percutaneous [ procedure not requiring surgery] is very attractive to any patient, but some patients still require surgery," says Tolan.

Despite the modes of treating coronary artery disease, the issue of preventative therapy remains.

Dr Vincent Maher, consultant cardiologist at Tallaght Hospital and medical director of the Irish Heart Foundation, says: "Angioplasty and bypass only relieve symptoms of coronary artery disease, but patients are still at a very high risk of a heart attack unless the disease causing coronary artery disease is dealt with."

The earliest signs of coronary artery disease can be detected from the age of 18 months, the process builds up in later years but is accelerated by risk factors such as smoking, diabetes, lack of exercise and genetic factors.

As a result, each person is responsible for his/her own outcome which can lead to severe coronary artery disease resulting in bypass or angioplasty. The process can be curtailed if plaque-stabilising treatments are put in place to aggressively treat these factors that lead to surgery or a procedure being carried out.

The main cause of heart attack is plaque rupture whereby the plaque in the artery can burst at any time without warning, says Maher.

"It does not matter how narrowed the vessels are, these plaques are still prone to bursting. Hence, if somebody does not need a bypass, or angioplasty, the plaque can still burst and cause a heart attack," he says.

As a result, being aware of your cholesterol intake, diet and exercise is imperative in the prevention of coronary artery disease.

Maher says: "There are many people, most who have had angioplasty or bypass, walking around Ireland believing they have had a cure. They haven't, they have had their symptoms relieved but they are still very vulnerable, unless they get plaque-stabilising strategies put in place."

Regarding the current epidemic of obesity in Ireland and throughout Europe, Maher says: "It is going to increase the incidents of diabetes and blood pressure from an early age. If the obesity epidemic continues, we would expect to see younger and younger people getting heart disease."

As a result, patients with coronary artery disease are partly responsible for their own condition. Despite the successes and risks associated with operations such as bypass or procedures such as angioplasty, they cannot eliminate heart disease.

In the short term they prevent symptoms from progressing, but they are not treating the disease. In the long term, coronary artery disease can only be treated by the patient, in conjunction with the support of experts in the field of preventative cardiology.

Otherwise, the disease will progress or one day suddenly rupture with a fateful result.