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A better bypass -

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Norman Swan: Now to a story that might prove handy one day. When you have three or more blocked coronary arteries or a blockage in what's called the left main coronary artery, also called the widow's artery (and you don't need too much imagination to wonder what that's about), then avoiding stents and going to open heart coronary artery bypass surgery is usually the best option. The trouble is that this surgery is associated with a risk of stroke. Some surgeons have blamed the heart bypass machine for this or unnecessary manipulation of the aorta which comes off the heart, which is why some surgeons try to do off-pump bypasses on the beating heart. The question, and it's a big one, is whether it makes a difference, which is why an international research group, led by Australians, has analysed is the evidence. With me in the studio is one of the senior authors, cardiothoracic surgeon Michael Vallely of Sydney and Macquarie Universities. Welcome to the Health Report Michael.

Michael Vallely: Thank you Norman for having me.

Norman Swan: Let's just get the context right here and the various procedures that are available, because it's largely an elderly group of people you're talking about here who need this.

Michael Vallely: That's not entirely correct, but yes, obviously coronary artery disease can happen in people in their 20s, and I've certainly operated on people up into their 90s, so it's a wide spectrum. But the average age, that has been consistent, is around the 67, 68-year-old mark, and certainly that has been responsible for…

Norman Swan: Young!

Michael Vallely: Of course, it gets younger every day, exactly! But I think the advances in cardiovascular medicine and cardiovascular surgery is one of the reasons the population is living so long now.

Norman Swan: We've done this story before on the Health Report a few years ago where people said, look, the pump is a dreadful thing, it can break off all sorts of rubbish which goes up into the brain causing cognitive difficulties and stroke. And you've got to get people off the pump. And so there was a lot of promotion of beating heart surgery in those days. And then it went off the boil and people have gone back to the pump. So what's the story here?

Michael Vallely: I think there's a couple of issues there. One is it's a technically more difficult procedure to do, and certainly there was some issues with the technical aspects of that.

Norman Swan: Because you've got a moving target.

Michael Vallely: Moving target, and positioning of the heart and also choice of patients and also training. I think we've been fortunate in that this surgery has been around for more than 20 years now and there's a group of us that are dedicated to doing that procedure. I think the other thing too is that people thought it was the heart-lung machine that was causing the trouble and not the aorta. The aorta is the main artery or the main pipe that comes out of the heart that delivers blood to the rest of the body. And as people age and as their comorbidities increase—diabetes, cardiovascular disease, smoking, obesity, et cetera—you can get disease within the aorta. And if bits of that disease break off and goes elsewhere in the body, particularly to the brain, that's how you have a stroke.

And so what we and certainly a group of surgeons that taught me at North Shore and other surgeons around the world thought that it wasn't actually the heart-lung machine that caused the problem, it was actually manipulating the aorta. And part of the heart-lung machine is to manipulate the aorta, put in cannulas to return the blood. And how you stop the heart is by putting a big clamp across the aorta to stop the heart, to do open heart surgery. So we've got a procedure, and the other researchers in this large meta-analysis have got a procedure where you can completely avoid manipulating the aorta and just perform the bypass grafts using inflow from other arteries.

Norman Swan: And just to clear up any confusion, there are procedures where you do operate on the beating heart, but you still manipulate the aorta. So it's not a guarantee that…

Michael Vallely: There's different degrees. There is a term that was coined by one of my training surgeons, John Brereton at North Shore, which is anaortic, which is a term that we've used as a simpler version of aortic no-touch. So essentially there's different degrees of aortic manipulation from absolutely no manipulation, which is the procedure that we've highlighted as the initial procedure within this network meta-analysis which looks at four different ways of doing this surgery, to minimal aortic manipulation, to a clamp manipulation and to a full-blown arrested heart and heart-lung machine with a cross clamp. So there's different degrees of aortic manipulation.

Norman Swan: And so what endpoints were you looking at in the analysis? Because you looked at basically the international literature in this field.

Michael Vallely: The international literature, it's interesting, the numbers look large, but in terms of the scale of the procedure they are quite small. But what we looked at, the major endpoint that we were interested in was stroke and neurocognitive injury. And the patients that had the procedure done with the minimal aortic manipulation had a much larger incidence of preoperative stroke and preoperative neurological problems.

Norman Swan: So they were at greater risk of stroke.

Michael Vallely: So a greater risk of stroke but they had a drastic reduction in stroke. So if you actually did a propensity score analysis between the groups the results would probably have been more impressive.

Norman Swan: So just to be clear, the surgeons were preselecting patients, saying, well, I'd better not touch the aorta because they are going to have a stroke. And so you are loading the dice against the results.

Michael Vallely: Loading the dice against results, and…

Norman Swan: But in fact they had reduced levels of stroke.

Michael Vallely: Yes, that's correct.

Norman Swan: And presumably that played out for people not at particularly increased risk of stroke.

Michael Vallely: Yes.

Norman Swan: So let's just then clear the space here, because you've got an army of interventional cardiologists whose mortgages depend on them putting in stents. You've got another army of cardiothoracic surgeons who also have mortgages…I'm being facetious…but…

Michael Vallely: I think it's a very valid point actually, Norman, yes.

Norman Swan: So when do you need bypass surgery and then what should you be asking your surgeon about beating heart surgery, if you need bypass surgery?

Michael Vallely: I think you come back…I think one of the issues is you need an institutional or a heart team approach to the management of patients with cardiovascular disease, so that patient…there's an agnostic view of what they need.

Norman Swan: So there's a team, that's the first question to ask.

Michael Vallely: Absolutely. And it needs to be done in a team, and certainly the European model I think we are lagging a little bit behind in Australia, but in a separate type of disease, and so structural heart disease and trans-catheter valves, we have hearts teams and the patient gets the correct procedure. But you're absolutely right, you've got different craft groups competing for the same procedure.

Norman Swan: So what are the indications for a bypass in a team basis?

Michael Vallely: The indications are obviously patients with complex coronary arteries, these patients, as you very elegantly pointed out in the introduction, with left main, with severe triple vessel disease, patients with poor left ventricular function. Certainly patients with diabetes do poorly with stents, patients who may not be compliant with medication that is required to keep stents patent. And certainly patients who need other types of heart surgery as well need bypass surgery on top of that.

Norman Swan: So you don't want to have a stroke but not every cardiac surgeon is trained to do beating heart surgery. So what are the questions to ask?

Michael Vallely: I think there's several things you should ask your cardiac surgeon. One is how many of these have you done? What are your results? And if not, then who should I be going to? And I think that's a very valid question to ask any doctor, not just your cardiac surgeon.

Norman Swan: Keep your hands off my aorta.

Michael Vallely: Yes.

Norman Swan: Michael, thanks for joining us.

Michael Vallely: Thank you, it's been a pleasure.

Norman Swan: Professor Michael Vallely of Macquarie and Sydney Universities, and Sydney Heart and Lung Surgeons.