This week’s study on cardiac stents, published in The Lancet, has certainly put the cat among the pigeons in the world of cardiology.
Percutaneous coronary intervention(PCI), first carried out over 30 years ago, involves passing a tube into the coronary arteries through which dye is injected. Any blockages identified can then be squashed back into the wall of the artery – a procedure called angioplasty – and a metal scaffold known as a stent placed in the diseased area to prevent further blockage.
Researchers at Imperial College London conducted a study on 200 patients who had one severely blocked artery to the heart. The blockage was severe enough to cause chest pain that limited the person's exercise capacity.
For six weeks, the research team gave the participants statins, aspirin and blood pressure medication, and then each patient underwent a routine procedure to insert a stent into the affected arteries.
Sham procedure
However, half of the group was, in fact, subjected to a sham procedure, where unknown to them, the tube was withdrawn and no stent was put in place.
Some six weeks later, all participants had an exercise test. To general surprise, there was no difference in the exercise tolerance between the stent and non-stent groups. For some, this is evidence of a placebo effect, in which the suggestive power of having a procedure performed is enough to bring about improvement.
Increasingly popular and with the advantage of avoiding open-heart bypass surgery, the stent industry has grown to the point where more than 500,000 procedures are carried out annually in people with stable angina. This is despite evidence showing that medication for angina is as effective as having a stent.
I must declare a personal interest here. Diagnosed with ischaemic heart disease some 12 years ago, I have had three stents inserted in that time. My first was in response to the sudden onset of angina, which was diagnosed as an acute coronary syndrome. This is a condition that can rapidly progress to heart attack and I was certainly appreciative of the intervention to relieve a 90 per cent blockage in one of my coronary arteries.
Chest pain
Ten years later, and in response to some atypical chest pain which was not precipitated by exercise, a repeat angiogram revealed significant blockages in two different vessels and I had two stents inserted.
Do I think that I could have avoided stenting? Not at all. But then I didn’t have the procedure for stable angina, which is a controversial area.
The latest research will certainly prompt a re-evaluation of such widespread use of coronary stenting. However, I would not expect any significant change in clinical practice before this relatively small study is repeated on a larger group of patients, with a longer follow-up time and using coronary events rather than exercise tolerance as the study end point.
Dr Muiris Houston is a medical journalist and health analyst