The angioplasty debate: When not to reopen blocked arteries

Dr. Vladimir Dzavik is the director of interventional cardiology at the University Health Network in Toronto, Canada's largest centre for the treatment of heart disease. He also chaired the Canadian study known as TOSCA-2, which was released in November and is revolutionizing the way cardiologists treat many post-heart attack victims.

So, you've had your first heart attack, you're lying in hospital recovering with the help of a bunch of new medications and now comes the big decision: Do you have an angioplasty and a stent inserted in that blocked artery to help restore blood flow to your battered organ?

For the past decade or so that would have been a no-brainer. Cardiologists would routinely order up an angioplasty. That meant having a tiny wire called a catheter inserted into the artery to break up the clot — the more modern versions have little balloons to hold open the artery while a tiny lattice-shaped tube called a stent is put in place.

But in November of this year, two new studies developed in tandem — one a Canadian study of 318 patients known as TOSCA-2, the other an international study of 2,166 patients known as OAT — challenged the very basis of these earlier assumptions.

The studies found that angioplasty and stents are no better than heart medication when it came to long-term survival and preventing further heart attacks. Indeed, the surgical approach even looks to have contributed to a slightly higher rate of second heart attacks among those examined.

There are two exceptions to the findings: Stents inserted within the first 12 to 24 hours of a heart attack are viewed as overwhelmingly beneficial; so are those in post-heart attack patients who are unstable and still experiencing significant chest pain.

But as Dr. Vladimir Dzavik explains, these new studies are dramatically changing the way cardiologists deal with their patients.

What was the most surprising aspect of what you found?

For years, many clinicians felt that a significant proportion of patients who suffer a heart attack and had a closed blood vessel — we're talking of roughly a third of overall heart attack patients — would benefit from opening this artery later, or beyond the normal 24-hour window.

What we found was that this was not the case and that is what makes this a practice-changing study.

In fact, this procedure may be associated with some harm, that being a trend to increased risk of a second heart attack after the procedure.

Why would there be an increase in heart attacks after angioplasty?

Well, for one, there is a small proportion of heart attacks that can occur at the time of the procedure or right after it. Inserting a stent can block a side branch and lead to further complications.

But we didn't just find this increased incidence [of secondary heart attacks] early on. It continued throughout the period of the study. Why would this happen? Well, any time you open an artery it can close again.

So the patients who were assigned to the medication-only side of the study, their damaged arteries remained closed and they would have had collateral channels to feed the heart muscle.

But if you open the artery with a stent, there is a chance, however small — we found it occurred in about nine per cent of our patients — that the artery can close again because of a second blood clot or further re-narrowing down the line.

This physical reopening of the artery through stents and balloon angioplasty, this has become standard fare in the heart-care business, hasn't it?

Yes, this is the majority of the kind of work I do. And this has become a very common approach in post-heart attack treatment. The majority of patients who have a heart attack undergo what we call a late reopening [of from three to 28 days after the original incident].

Early opening, especially within the first 12 hours, definitely improves outcomes, improves survival and reduces mortality. We're talking about those who come later on to the procedure and for whom the clot-busting medication hasn't worked.

That we estimate to be about a third of all patients with a heart attack who will end up with a closed artery. And the routine among cardiologists has been that these should be opened.

Has that view now changed because of this study?

We are seeing a change in our centre and I've been giving talks in other centres around the country and physicians, I believe, are changing.

It was a landmark study and there are no questions about the results. So doctors are looking at this very seriously and realizing that the angioplasty/stent procedure, as we do it today, is not effecting a positive outcome.

Therefore we are coming around to viewing this as an unnecessary procedure, and cutting back on it should make for potentially significant savings in health-care dollars.

Is this a hard sell for patients who've been told they have a blocked artery and know there is a way to have it reopened?

Angioplasty is a fairly simple procedure but it's a procedure not without risk.

The message here is that as much as these patients might want to have their artery open, they need to understand that the procedure is not free of risk and that medical therapy, if medications are taken properly, works just as well.

At UHN, we've actually changed our practice and are doing fewer of these procedures now. Once we understand that the artery is blocked completely, we don't go routinely now to an angioplasty/stent procedure unless we know that this patient has had significant recurrent symptoms or is in some other way unstable.

Does this put a greater onus then on even earlier intervention, on getting as quickly as possible to that closed artery?

Yes, but there are really a couple of issues here.

First, people have to understand that they must seek help as early as possible if they experience something they haven't had before or if they recognize this as something that might be related to the heart.

The second issue is that we really have two different ways to open these arteries early. One is by angioplasty and stenting, and the other is by thrombolytic or clot-busting drug therapy.

Angioplasty/stenting works in 90 per cent of cases but it is not available everywhere. Not every community hospital can afford this kind of centre.

Thrombolytic therapy, on the other hand, is available pretty much everywhere but it is only effective in at most 60 to 70 per cent of patients. So we have a bit of a schism in how we practise that somehow has to be bridged.

We know that either of these therapies is effective within the first 12 hours and probably up to 24, but the longer you wait the less the benefit.

The most lives saved occur when patients present to the emergency room and have their arteries open by the balloon/stent within 90 minutes.

Unfortunately that doesn't occur in very many centres on a routine basis. We still have all kinds of system work to do to make that happen.