Treating CTOs: Technique and technology
- Posted on: 6/19/08
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Approximately how many are chronic total occlusion (CTO) patients?
Eight to ten percent are CTO attempts.
What is your crossing success rate?
Our crossing rate now is in the range of 80%. There are nine interventionalists working at the St. Luke’s laboratories, so that percentage represents the average success rate for the group.
Why is it important to treat CTOs? Should all CTOs be treated?
There are two really compelling reasons why CTOs should be attempted. One reason is that there is some very good data now showing that you can improve left ventricular function by successfully opening a chronic total occlusion, particularly if the initial ejection fraction is less than 60% and particularly if the CTO is less than three months old.
Why less than three months old?
These patients are closer to an acute myocardial infarct, so the chance of improving the left ventricular function is a little better in that group.
The second reason is that there is definitely an improved long-term survival in patients that have successful opening of a CTO. St. Luke’s has a 20-year experience with a 10-year follow-up of over 2,000 patients that have had angioplasty and stenting of a chronic total occlusion. At 10 years, the survival rate for successfully opening a CTO is 73%; in those patients where you fail to open the artery, the survival rate is only 65%. It’s a very significant survival advantage if you open up a CTO, making this the most compelling reason to attempt to open a CTO. Our data has been confirmed now by data from Japan and also by Dr. Serruys’ data from Rotterdam. The Rotterdam experience looked at 874 patients. The five-year survival for opening a CTO was 93.5%. If they failed to open, survival was only 88.0%.
Where are you seeing most CTOs?
The majority of them are actually right coronary arteries (RCA). Second would be left anterior descending (LAD), and third would be left circumflex. If you look at the 10-year survival based on the CTO location, the patients that do the best are patients that have a CTO of the LAD. These patients’ 10-year survival is 77% with a successful crossing versus 60% for those who failed to have their LAD opened. The next best data is from the RCA, and we find no long-term survival advantage for the left circumflex.
Can you comment on the concept of a second attempt to cross a CTO?
Most data would confirm that if you fail to open a CTO, there is a 50“60% success rate on a second staged attempt. I believe you learn a lot with the first approach, and you may make some mistakes with the wires in the first approach, so it’s really worthwhile to bring the patient back for a second attempt.
What wires do you tend to favor?
There are some fairly standard approaches now. Increasing success rates are the result of the development of the Asahi family of wires. The Asahi Confianza, the Confianza Pro wires and the Miracle Bros wires. The Miracle Bros wire increases from a 3-gram up to a 12-gram wire. However, we really need wires that are even heavier. Overseas they have 15-gram and 20-gram wires. By grams, I mean the stiffness of the tip of the wire, so the higher the gram number, the stiffer the tip, and the better the chance of penetrating through a very fibrotic or even calcified chronic total occlusion. The other family of wires that is useful is the Medtronic Persuader wires, and they also come in a 3-gram up to a 9-gram wire. These two groups of wires have made a big difference to our overall success rates.
Do you use them exclusively for CTOs?
I use them almost exclusively for CTOs. Very occasionally, we might use a 3-gram Miracle wire for crossing into a side branch through a stent.
What about guiding catheters and balloons?
I use 8-Fr guiding catheters, usually standard-shaped guiding catheters, a JR4 8-Fr guiding catheter on the right, and a SL4 8-Fr guiding catheter on the left. The only thing about the guiding catheters is the sizing of 8 Fr versus the 6 Fr. Most people use 8 Fr catheters because they give more support.
We use extremely low-profile balloons, 1.5 to 2 mm. The lowest profile balloon available is the Sprinter balloon, which is a Medtronic Vascular balloon. On the rare occasion where you can get a wire across the chronic total occlusion but you can’t follow it with a balloon, we will use the laser or the Rotablator. That happens less than 1% of the time. For the vast majority of the time, if you penetrate with a wire, you can follow with a low-profile balloon.
When you’re dilating the lesion, is there anything in particular that it’s helpful to keep in mind?
Start with a very low-profile balloon and then increase the size of the balloon to the final vessel size. The most important thing when you’ve opened the CTO is to use intravascular ultrasound (IVUS) to correctly size the vessel. IVUS will demonstrate the true size of the artery, so you don’t undersize the stent when you place it. Most of these chronically-occluded arteries are negatively remodeled, meaning they look smaller, angiographically, than they really are. The IVUS evaluation shows the true size of the vessel so a stent can be sized appropriately.
Can you describe a recent case?
We recently had a total occlusion of a right coronary artery where the distal vessel was filling by collaterals arising from the left anterior descending. In this type of case, the first thing to do is put in two catheters. A guiding catheter was placed into the right coronary artery to get an antegrade injection into the right coronary, and a diagnostic catheter in the left main coronary artery, so that when we visualized the left main coronary artery, we could see the collateral filling of the distal right coronary. This technique is a double-guide injection. This demonstrates the exact length and the orientation of the chronic total occlusion.
The case I’m thinking of was a blunt occlusion, so I started with a Confianza Pro wire. We got it to start into the vessel but it then went into the subintimal space. We left the first wire there, and followed with a second wire, which we deflected off the first wire into the true lumen. This is the so-called parallel wire technique, which has been championed by the Japanese, Drs Tamai and Katoh. It is a very effective way of opening these vessels. As part of this technique, you seesaw the two wires. In other words, you pull one wire back and advance the first wire, and if that wire doesn’t go into the true lumen you pull that wire back and advance the other wire, so the two wires are in a to-and-fro movement, trying to find the true lumen.
It seems that despite all the new technology coming out, that there needs to be an equal application of technique as well as technology.
Yes, technique is number one. Technology is number two. It requires very experienced hands to take on these chronic total occlusions and 50 or 100 procedures before reasonable results are achieved.
What are the causes of failing to open a CTO?
Number one is the tortuosity of the vessel. If the vessel is very angulated prior to the point where it is totally occluded, it is very difficult to advance wires and catheters to reach and effectively open the CTO. Number two is calcification. A heavily calcified vessel is much more difficult to open than a vessel with moderate to mild calcium. A very tortuous, heavily calcified vesselwill have a failure rate of 50%.
Have drug-eluting stents had an impact?
They’ve had a big impact. The PRISON II trial looked at Cypher stents versus bare metal stents in 200 patients with CTOs, with a six-month follow-up. The target lesion revascularization rate for bare metal stents was 19% and for the drug-eluting stent, 4%. The MACE rate at six months was 20% for bare metal stents versus 4% with the drug-eluting stent. The restenosis rate was 36% for bare metal and 7% for the drug-eluting stent. There’s not much doubt now that drug-eluting stents are much more effective in chronic total occlusions.
So that may account for the increased interest in treating these patients?
I think that’s right. The two things that account for the increased interest are number one, the development of the subspecialty wires that we talked about, and the second thing is the use of drug-eluting stents, with a reduction in restenosis and reocclusion. Six-month reocclusion rate in the PRISON II trial was 13% for bare metal stents and only 4% for drug-eluting stents. The development of the specialty wires in particular allowed us to achieve higher success rates.
Any in-house studies ongoing or planned?
The only one that’s ongoing right now is the Cypher ACROSS study. David Kandzari at Duke is the principal investigator. It’s not a randomized trial, but a registry, so all of the patients that we successfully cross have Cypher stents placed, and they are coming back for a 12-month angiographic follow-up. We’ll know precisely what our in-stent restenosis and reocclusion rate is, at least for the Cypher at 12 months.
How do you schedule your CTO cases?
I have set up a CTO day, so that instead of doing these patients on my everyday schedule, I cluster them on one particular day. I’ll bring in 4 or 5 chronic total occlusions and devote the whole day to taking care of these patients. I have the luxury of doing that because I’ve got multiple labs, so my colleagues can do the acute cases, and allow us to do these cases all on one day. It concentrates your effort. One of my other colleagues scrubs in with me, so there are two cardiologists devoted to CTOs on that day. It also allows me to use any new wires and devices that come along. We’ve also invited physicians from outside our area. We have six invited physicians that will come and learn techniques on how to open chronic total occlusions. I would emphasize that this day has really made the difference for us.
Dr. Rutherford can be contacted at [email protected]