International Andreas Gruentzig Society: Preserving Myocardium During Acute Myocardial Infarction
- Volume 14 - Issue 7 - July, 2002
- Posted on: 8/1/08
- 0 Comments
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Howard Cohen: What routine pharmacologic therapy are you currently using in your lab for patients with acute myocardial infarction? Do you use anything in a routine fashion, or do you restore blood flow and see what happens? Are you routinely using IIb/IIIa receptor antagonists or adenosine?
Paul Overlie: As you might imagine, I am not the one to ask about pharmacologic therapies. We handle a large number of acute myocardial infarction therapies every year and have long believed that minimal but rapid instrumentation of acute infarcts is the best way to treat them. I always worry about the correct sizing of the devices used when no-reflow occurs. Our routine strategy in a patient with acute myocardial infarction is to give heparin, aspirin, Beta-blockers, and sometimes Plavix if there is time. We then take the patient to the cath lab for cardiac catheterization to determine risk stratification, find the culprit artery, open it, and now stent it as well. Roughly a third of the time, IIb/IIIa inhibitors are used, but otherwise just heparin. I don? know how frequently no-reflow occurs ?perhaps others can answer that question ?but it is certainly extremely uncommon in our experience. In my opinion, the timeliness of the intervention is the most crucial factor in these cases.
Howard Cohen: That is very clear. Much of the data show that the earlier we can intervene, the better the outcome. Tom, what is your routine ?ocktail??
Tom Linnemeier: The problem I have with no-reflow is that the predictive value of which patients will have no-reflow is extremely low. I agree that if you look at the statistics, there is a higher incidence of no-reflow the longer you wait to take the patient to the cath lab. I also agree that adenosine is a nice cocktail that works sometimes, but not every time. I think the AngioJet, because of its size, can sometimes actually make distal embolization worse. However, in some of the trials, it has been shown to lessen distal embolization. The whole concept of no-reflow is a very interesting one. Although I treasure all the moments I had with Andreas Gruentzig, I think the only thing he was wrong about was in the area of clinical outcomes. That is, you don? want to throw anything downstream when performing routine angioplasty, and yet I think we do just that all of the time. It is probably more apparent during acute myocardial infarction, less apparent in angina and somewhere in between in the case of unstable angina. Of all the topics that Kirk Garratt and Jim Zidar put on the agenda for this meeting, this particular one has the most potential to be solved within the next three to five years. I think it will be solved with a combination of distal embolic protection devices and pharmacologic solutions such as IIb/IIIa inhibitors. A succession of trials have shown the superiority of acute angioplasty over medical therapy or thrombolytics, yet the biggest problem we currently face is that a large number of patients still don? ever get to the cath lab. The problem is primarily a logistical one in many instances, and the only way to solve it is to have more interventional cardiologists on shift work if possible. Many cardiologists resist the idea, however.
Howard Cohen: Brian, in terms of pharmacology in the cath lab, what are you currently doing at Temple?
Brian O’Murchu: Our approach has been very similar to that of the other panel members here. That is,we try to get the patients to the cath lab quickly. There are a number of interesting possibilities related to the area of direct thrombin inhibitors which have not been looked at in this context. The free fatty-acid inhibitors also have some potential in terms of protecting from ischemia in myocardium, and I think it is worth investigating whether they might have an effect on microcirculation as well. We have not been innovating “outside of that box.” Also, we should discuss the importance of regularly updating our “door-to-balloon” time because we think we do a good job and have all said that the door-to-balloon time is perhaps the most powerful agent we currently have. I wonder how well we are all doing in that regard.
Howard Cohen: Those are very good points, Brian. Let me ask the panel members, in regard to pharmacology, in what percentage of patients are you using a IIb/IIIa receptor antagonist and are you administering it I.V. or I.C.?
Brian O’Murchu: We administer it intravenously in the case of myocardial infarction in those patients who meet the typical ST-segment elevation criteria. We administer it in 90% of our patients.
Howard Cohen: Tom, how about your lab?
Tom Linnemeier: Yes. We administer it intravenously. There are data out there to support large molecule versus small molecule during acute myocardial infarction.
Howard Cohen: And Paul, how about your lab?
Paul Overlie: Somewhere between 30% and 50%, depending on whether the patient comes from well out in our region or from nearby.
Howard Cohen: Let me ask you another question. At our institution, we frequently receive calls from allied hospitals located some distance away. Thus, I would say that at least 50% of our intervention patients, or perhaps even 75%, are flown in by helicopter. Western Pennsylvania has a helicopter system established in which helicopters are available throughout the region, making it possible to transport patients fairly quickly to the hospital. However, there is still a time delay. At the very best, there is about a 30-minute delay from the time we receive the call until the patient arrives in our cath lab. That delay can be up to an hour or an hour and a half if the patient is having a problem — or even two hours sometimes. If the patient is already in your hospital’s emergency room and is coming directly to your cath lab, it is of course easy to keep the door-to-balloon time down. But if the patient is, say, an hour or more out, what do you think about the combination therapy of lytic and IIb/IIIa? Do you recommend that to the emergency room physician or do you tell him/her to just send you the patient for treatment?
Tom Linnemeier: Yes, that is the dilemma. When I was at Indiana Heart Institute, we actually got to the point where there were up to 88 cardiologists spread across the state. There were about 45 cardiologists at the mothership of St. Vincent Hospital and the remainder at various clinics in Lafayette, Kokomo, Anderson, etc. The cardiologists who are out in the field — let’s say Lafayette — are located about a 45-minute drive from St.Vincent Hospital, which represents maybe about a 20-minute helicopter ride from the mothership hospital. These cardiologists absolutely must know what the patient is going to receive on the other end when he/she arrives at St. Vincent. And it is extremely difficult for those doctors to have a syringe full of t-PA or t-NK in their hand and realize that they can achieve a 60–70% reperfusion rate within the next hour to not give that drug unless he/she is absolutely positive that someone is on the other end waiting with an open cath lab — no matter when, 24 hours a day. It would depend, therefore, on the time of day. If the event occurs during the daytime, there would be an open cath lab between 7:00 am and 7:00 pm and most patients would be sent to the cath lab at St. Vincent Hospital where they are likely to receive a IIb/IIIa receptor blocker, aspirin, beta-blockers, etc. If, however, the event occurs at 2:00 am, the scenario is usually different. Typically, patients in the outlying areas would end up receiving the lytic — sometimes the IIb/IIIa — and then would be transported to St. Vincent. The patient often would stabilize, but if not, he/she would be sent to the cath lab. I am not saying that this is the best system, but that’s the way it worked in Indiana. As I said earlier, we interventional cardiologists are an odd bunch because we pretend we are not working when we are on call, but we really are working. Some nights you get sleep, while others find you up answering calls. So I think we should just call it what it really is: work! And if you truly believe that PTCA for acute myocardial infarction is the best thing to be doing for patients, then you ought to be available to do it 24 hours a day, seven days a week, 365 days a year.
Brian O’Murchu: I have a quick question, Tom. Were the patients getting full-dose lytic therapy?
Tom Linnemeier: Yes.
Howard Cohen: We have six interventional cardiologists at our institution, so it depends on the interventionist and the time of day. If I know the patient is an hour or more away, I advise the physician to administer a half-dose of lytic and a IIb/IIIa inhibitor and then have the patient brought in for evaluation. If the patient is totally pain-free and the ST-segments have completely resolved, we may not study the patient that night, but bring the patient in the next morning. If, on the other hand, there is any sign of an ongoing problem, we will study the patient at that time and intervene if necessary.
Let me ask the panel this question: In patients with acute myocardial infarction, what percentage of them will be treated with a distal protection device when it becomes readily available?
Paul Overlie: I am going to skip the question right now about distal protection devices because I want to comment on our institution’s long history with acute infarct therapies. Two-thirds of our patients come from outside our county. A network of active air transportation with a variety of aircraft are available. Throughout the years, my colleagues and I have watched the thrombolytic trials in progress and have been involved in most of the acute infarct trials. We have also been in discussion with Steve Ellis and colleagues at the Cleveland Clinic about the value of rescue angioplasty and agree that it is a very valuable therapy, but we are often accused of the “in our hands” issue that comes with a lot of the investigations. That is, you have a small group of skilled operators who are used to doing the procedure. For many years, we took virtually every patient to the cath lab. Listening to this discussion today, we have also lapsed into that too. We can transmit 12 leads from helicopters, from the ground, anywhere. I can look at the situation from my home, and if I can see the 12 leads come through, the ST-segments are no longer elevated and the patient is pain-free, I won’t necessarily have the patient brought immediately to the cath lab. But for those patients with ST-segment elevation infarcts, we find that it’s crucial to get them to the cath lab early, minimally invade them and get their arteries open.
Howard Cohen: To what extent do you think primary angioplasty should be performed in outside hospitals with skilled operators where there is no surgical back-up? As you know, in certain states such as Massachusetts, an ongoing program called Special Project looks at primary angioplasty in small hospitals performed by physicians who are skilled but have no surgical back-up. In Minnesota, I believe, a similar type of program exists. Let’s move ahead now and we can perhaps revisit that topic later.
I would like to return to the question about the percentage of interventions for acute myocardial infarctions where there is thrombus burden for which distal protection devices will be used: 50%, 100%?
Brian O’Murchu: I think our institution does this extremely well. Because of the technical ease of the procedure we perform, I would say that roughly 5–10% of the patients we treat receive distal protection devices, and these are patients in whom we visually detect a large mass of thrombus.
Howard Cohen: Tom, what do you think?