Stent it or just bypass?

By the year 2020, coronary artery disease is set to account for one third of all the deaths, in India. Coronary artery disease causes blockages in the vessels restricting the blood supply to the heart muscle. As the blockage advances, the threat to the patients’ life increases. The treatment modalities available include medication, surgical intervention or percutaneous coronary intervention (PCI)

Dr Vasundhara Atre

Posted On Wednesday, August 29, 2007   


Fixing the block
Using surgical intervention, the coronary artery bypass surgery, the existing blockages are ‘bypassed’, like creating a detour on a blocked road. Either a vein or an artery, from within the body, are used to create the alternative route. The flow is restored well beyond the areas of block.
 
Today, the internal mammary artery located within the chest wall is used for this technique. These have inherent advantages, which protect them from getting blocked in the long run. Surgeons are now performing the surgery while the heart continues to beat. This is called as the ‘beating heart surgery’.
 
Stenting the artery
Using coronary angioplasty, the blockages are dilated and mechanical devices called stents implanted at the site of the blockage. The stents treat the focal area of narrowing, thus relieving the obstruction.
 
In the last few years, drug-eluting stents have been introduced. Dr Matthew, cardiologist and Director of Cardiology, Apollo Hospital and Director of Madras Medical Mission, explains, “In the drug eluting stents, the drug is bound to a polymer in the stent from which it releases slowly. The released drug inhibits the inner lining of the artery from proliferating, preventing reblockages.”
 
In the last two decades patients have preferred PCI as it avoids a surgery, require a shorter hospital stay and can be done in the same sitting as the angiography.
Dr Ramakant Panda, vice chairman and consultant cardiothoracic surgeon, Asian Heart Institute, asserts, “Whenever any new procedure is introduced it tends to be overused, as has happened with the stents. Over time its limitations are being realised.”
 
The Concerns
The use of PCI gained momentum abroad as it was found to be cheaper than a bypass surgery. In India, surgery remains the cheaper option.
 
Eminent cardiologist Dr B K Goyal, President of Indian College of International Cardiology, says, “The stent cost ranges from Rs 45,000 to Rs 1,25,000 depending on the company and the type. The coronary artery bypass surgery often costs half of this in India.”
 
“But this may not be a one time cost. Patients may require a second intervention, in case of a reblockage,” adds Dr S S Bhattacharya, cardio-thoracic surgeon, Breach Candy Hospital, Bombay Hospital and Lilavati Hospital.
 
Dr Ashwin Mehta, Director of Cardiology, Jaslok Hospital explains, “The biggest drawback with angioplasty compared to bypass surgery was the restenosis rates after angioplasty. The restenosis rate has reduced from 30 to 40 per cent in the coronary angioplasty era to four to eight per cent in the drug eluting stent era.” Dr Matthew explains, “The restenosis still occurring in these stents is because of the reaction to the polymer used in the stent.”
 
Dr Goyal adds, “Though stents are considered safe, the chance of closure of the stent in the first 72 hours or in the first week is around one-two per cent. Over the four years that the drug eluting stents have been introduced in India, late stent thrombosis (blockage) even after a year is also seen.” He also cautions that the long term effects of the drug released from the drug eluting stent on the body are not known.
 
Dr Mathew says, “Angioplasty and bypass surgery both carry good long term results. After the introduction of drug eluting stents, the concern about the stent closure rate is comparable to the graft closure rate after surgery.”
 
Dr Bhattacharya explains, “While surgery bypasses the areas that could potentially develop into blocks over time, PCI generally treats proximal lesions and is more susceptible to progression of disease. Even if “in -lesion” stenosis is zero, about half of the patients undergoing PCI would still require a repeat procedure.”
 
 
When is stenting chosen over bypass surgery?
Dr Goyal explains, “It is the procedure of choice in patients who may not be fit for surgery, as a stop gap arrangement to stabilise the patient till such time that surgery is possible. Also in patients who require a re-do coronary surgery it can be used to open up the bypass grafts thus avoiding another surgery. It should be situation based.”
 
Explains Dr Mathew,”Restenosis is a gradual progress. A meticulous follow up with stress or stress thallium tests at regular intervals and repeat angiograms are advised.”
Dr Bhattacharya summarises,” The long term benefits of bypass surgery especially with bilateral mammary grafts has been documented. It has translated into more relief of angina, lower revascularisation rate, and lower rate of major adverse cardiac events.”
 
Dr Panda opines, “The revascularisation strategy should be situation based. While some patients will benefit from stenting, certain groups of patients like those with severe triple vessel disease and diabetes will benefit more from surgery.”
 
Dr Mehta adds, “The evolution of third generation stents is addressing the concern of reblockage due to the stent polymer. An inert polymer stent now available has an extremely low incidence of restenosis. Bio-absorbable stents where the polymer would disappear in 180 days are being developed. Bio-degradable stents are also under study.”
Dr Goyal sums up,” With the advent of angiogenesis, neovascularisation and the use of stem cell therapy, especially in patients with poor heart function, both bypass surgery and angioplasty may soon be a thing of the past.”


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