Professor Colin Berry, University of Glasgow
Heart attacks are very common, but thankfully many more people are surviving them these days. The downside though is that victims often suffer health effects afterwards, like chronic heart failure, despite getting to hospital quickly and undergoing emergency treatment. It turns out that opening up blocked arteries that cause heart attacks tackles only half the problem. To explain why, and what happens when a person suffers a heart attack, Colin Berry, professor of cardiology at the University of Glasgow spoke to Chris Smith...
Colin - Classically, it’s the sudden blockage of one of the main arteries in the heart and that is typically caused by the breakdown of the wall of the heart artery because it’s diseased. Fatty plaque has accumulated at one or more places, the plaque ruptures, that exposes the constituents of the wall of the artery to the blood and normally they don’t meet, but when they do they’re not a great mix and a blood clot forms and that blood clot leads to loss of flow in the heart artery that is experienced by the patient as chest pain.
Chris - Does that mean that the heart downstream of that blockage, that part of the heart is destined to die unless someone like you comes along?
Colin - Yes. Bluntly, that is the case and, within 60 minutes almost certainly, some of those heart muscle cells will have started to die off and within 2 hours it will be threatened and beginning to die off almost irrecoverably.
Chris - What’s the current gold standard treatment? What’s the best way do we think at the moment of managing a person in that situation?
Colin - The whole team is working in emergency care circumstance to achieve restored flow in the heart artery as quickly as possible. We put a plastic tube in the wrist, we put a long catheter to the heart arteries, we inject dye using camera imaging, and we identify the blocked artery and, as quickly as possible, we pass a wire through that blockage, open the blockage by placing either a balloon or, indeed, sucking out the clot. Whilst the situation looks so much better with flow restored in the heart artery, I know from my research that there is a different story that is operative at the level of the heart muscle.
Chris - Go on…
Colin - All the small vessels in up to half of patients are all blocked.
Chris - What do you mean?
Colin - So the treatment pathway focuses on the main artery, which is large, but that artery has myriads of small vessels. Imagine the arborisation from a tree; these small vessels and all the little leaves are all blocked with microclots.
Chris - Is that something that happened at the time that the patient had the initial event or are you saying that in going in and focusing on getting that clot out and opening up the artery, all we’ve done is export the problem downstream? We’ve broken bits of it up and they’ve floated off down the artery and lodged making more blockages downstream?
Colin - Yes, that is a very likely scenario.
Chris - So what you’re saying is you have taken patients in in which this intervention has been carried out and you can see evidence that these vessels are blocked after what we currently regard as the gold standard treatment of unclogging arteries?
Colin - It represents a limitation of medical practice. We have focused on the main life-threatening problem and successfully treated the patient in that regard, but it has left a legacy of problems within the small vessels of the heart that can lead to heart failure in the longer term.
Chris - What are you proposing to try and do about this?
Colin - Historically heart attack was treated with a clot breaking drug. What we propose to do here is to give a small dose, a fraction of the dose, directly into the heart artery to break down all those microclots. That is the focus of this new trial called Ttime.
Chris - The idea being then that you go in, do what you’ve just described. You still open up the artery but anticipating that you will dislodge stuff that’s going to go downstream and block those vessels. Anticipating that’s going to happen, at the same time you’re going to put in some clot busting chemicals which will hopefully prevent those other small blood vessels getting blocked or unblock them if they are blocked already, and that should reduce the risk of onward complications?
Colin - And we have to wait for a couple of years to know the answer to that question.