Some of the most frustrating moments during a complex angioplasty happen after you think you have already solved the difficult part.
You get the guidewire across a very tight blockage. The wire is exactly where you want it. Then you try to pass a balloon over it.
It won’t cross.
You try a smaller balloon. Still nothing. Sometimes even a microcatheter will not pass.
This is one of the situations where excimer laser coronary atherectomy (ELCA) can be extremely useful.
The word “laser” makes the procedure sound rather more dramatic than it actually is. We are not firing a beam down an artery and burning our way through a blockage. The coronary laser is a very small catheter that travels over a guidewire and delivers short pulses of ultraviolet energy to the tissue immediately in front of it.
Used in the right situation, it can create just enough of a pathway to allow the rest of the procedure to move forward.
I have had a long association with this technology. While practising in the United States, I had been using and proctoring laser coronary procedures for several years, helping other interventional cardiologists adopt the technique and use it safely in complex cases.
So when coronary laser technology was commercially introduced in India in 2021, it was particularly satisfying to bring that experience back with me. I subsequently performed and proctored what was reported at the time as India’s first coronary laser atherectomy following its commercial launch in the country.
The milestone was exciting, of course. But what interested me more was why the laser was needed in the first place.
Conventional equipment could not adequately negotiate the lesion.
The laser allowed us to solve that problem.
That remains the way I think about ELCA today. The laser itself is rarely the point. Solving the problem is.
What does a coronary laser actually do?
The excimer laser catheter contains optical fibres and delivers ultraviolet light at a wavelength of 308 nanometres.
Its effects occur over a very shallow distance. Rather than behaving like a surgical laser cutting through tissue, it modifies microscopic amounts of plaque, fibrous tissue, thrombus and other material immediately in front of the catheter.
For most patients, the simplest way to explain it is this:
We are trying to create enough room for the equipment that needs to come next.
That might be a balloon. It might be an imaging catheter. It might be another device used to prepare the artery. A stent may eventually be required, depending on the lesion.
Laser is usually one step in a much larger procedure.
Can laser open a 100% blocked artery?
This is where the terminology can become confusing.
A chronic total occlusion, or CTO, is an artery that has been completely blocked for a prolonged period. Getting a guidewire safely through a CTO can be technically demanding, and modern CTO PCI has developed a number of specialized ways of achieving that.
Laser does not simply replace those techniques.
In most coronary applications, we first need to get a guidewire safely across the blockage.
Occasionally, though, we succeed with the wire and then encounter a different problem.
The wire has crossed the CTO, but the balloon will not follow it.
Nor will the microcatheter.
This is what we call a device-uncrossable CTO, and it is one of the situations in which laser can be very helpful.
One useful feature of ELCA is that the catheter can travel over a conventional 0.014-inch coronary guidewire. If we can bring it to the resistant portion of the blockage, laser energy may modify enough tissue to allow a balloon or another device to cross.
So can a laser help open a 100% blocked artery?
Yes, in selected cases.
But that is very different from saying that a laser can simply burn its way through any CTO.
It cannot.
Why not just use more pressure?
Because sometimes pressure is not the problem.
If the balloon cannot even reach the lesion, inflating it harder is obviously not an option.
Even when a balloon does cross, coronary lesions resist treatment for very different reasons. One may contain dense calcium. Another may be predominantly fibrotic. Another may contain thrombus. Sometimes the problem is inside a previously implanted stent. Occasionally an old stent has never fully expanded because of calcium underneath it.
This is why modern complex PCI involves much more than balloons and stents.
Depending on the problem, we may use specialized balloons, rotational atherectomy, orbital atherectomy, intravascular lithotripsy, laser, or combinations of these techniques.
Increasingly, we also use IVUS or OCT, which allow us to image the artery from the inside.
That has changed the way we approach many difficult lesions.
Instead of simply asking, “Why won’t this open?”, we can often see the reason.
Is there a thick ring of calcium?
Is an old stent underexpanded?
Has tissue grown inside the stent?
Is the vessel actually smaller or larger than it appears on the angiogram?
Once you understand the problem, choosing the right tool becomes much easier.
Laser, rotablation or IVL?
Patients occasionally ask me which of these is “best.”
There really isn’t a useful answer to that question.
They do different things.
A heavily calcified lesion that can already be crossed may be an excellent situation for rotational atherectomy or intravascular lithotripsy.
A lesion that no balloon can cross presents a different challenge.
A previously implanted stent that has not expanded properly presents yet another one.
Laser is particularly useful in certain device-uncrossable lesions and selected problems involving previous stents or thrombus. It also has a role in some calcified lesions, but I would not describe it as the default treatment for severe coronary calcium.
The skill in complex PCI is not simply having access to every device.
It is knowing which device solves the problem in front of you.
One small detail that matters: saline
When we use coronary laser, we flush the artery with saline before and during laser delivery.
This sounds like a minor technical detail, but it is important.
Blood and X-ray contrast can interact with laser energy and generate bubbles and pressure waves. Saline helps clear them away from the tip of the catheter and makes energy delivery more predictable.
It is a good example of why experience with these technologies matters. A sophisticated device is only as good as the technique with which it is used.
Does laser mean another stent?
Not necessarily.
If laser is being used during treatment of a new coronary lesion, the final procedure may well involve a stent.
But one of the other settings in which laser is useful is a problem involving an existing stent.
A stent can sometimes narrow again because tissue has grown inside it – what we call in-stent restenosis. In other patients, the original stent may never have expanded properly because of resistant calcium or tissue beneath it.
In those situations, simply putting another stent inside the first one may not address the underlying problem.
We first need to understand why the stent failed.
This is another reason IVUS and OCT have become so valuable.
How successful is laser angioplasty?
I am cautious about giving patients one percentage.
Laser is used for such different problems that a single “success rate” can be misleading.
A relatively straightforward in-stent problem is not comparable to a previously attempted, heavily calcified CTO in which multiple devices have already failed to cross.
Published contemporary series have reported high procedural success when ELCA is used appropriately, but results depend on the lesion, the reason laser is being used, the equipment available and the experience of the operator.
The more complex the case, the less useful a headline percentage becomes.
When I review a difficult angiogram, I am much more interested in why the previous strategy failed than in quoting a generic success rate for one particular device.
What are the risks?
Laser-assisted PCI carries the same broad categories of risk as other complex coronary procedures, including dissection, perforation, loss of blood flow and, rarely, bleeding around the heart.
These complications are uncommon, but they are real.
The risk also depends greatly on the situation in which laser is being used.
A laser used inside an old stent is very different from a laser being used during an exceptionally difficult CTO PCI.
Registry studies have found higher complication rates when laser is used in CTO procedures. That has to be interpreted carefully because the CTOs requiring laser tend to be among the most difficult cases in the first place.
In practice, the decision is not whether laser has zero risk. Nothing we do inside a coronary artery has zero risk.
The question is whether laser offers a sensible way forward in that particular lesion compared with continuing to push equipment that simply will not cross.
Technology is useful. Judgement matters more.
I enjoy complex coronary intervention partly because the technology continues to evolve.
We can treat coronary anatomy today that would have been extraordinarily difficult when I began training.
But having more technology does not automatically mean performing better procedures.
Sometimes laser is exactly what a case needs.
Sometimes it is rotablation.
Sometimes IVL.
Sometimes the best decision is bypass surgery.
Sometimes medical treatment is the better option.
And sometimes an artery simply does not need to be opened.
The technology has to serve the patient, rather than the patient becoming an excuse to use the technology.
“They told me the blockage cannot be opened.”
I hear this fairly often from patients with chronic total occlusions.
The first thing I try to understand is exactly what they were told.
There is an important difference between:
“This artery should not be opened.”
and
“We tried to open this artery and could not.”
They are not the same statement.
Not every CTO should be treated with PCI. There should be a clear clinical reason to attempt the procedure – most commonly persistent symptoms despite appropriate medical therapy, together with the overall coronary anatomy, heart function, ischemia where relevant and the patient’s other treatment options.
At the same time, an unsuccessful first procedure does not necessarily mean that an artery is permanently untreatable.
Modern CTO PCI has a considerably larger toolbox than conventional angioplasty: specialized wires and microcatheters, antegrade and retrograde techniques, dissection-re-entry strategies, intravascular imaging, atherectomy, lithotripsy and, in selected situations, excimer laser.
For someone who remains symptomatic after an unsuccessful CTO or complex PCI attempt, it can therefore be reasonable to have the original angiogram reviewed by someone who regularly performs complex coronary intervention.
Sometimes the answer will still be that another attempt is not worthwhile.
Sometimes there is another option.
The important thing is to understand why.
My bottom line
I had already spent several years using and proctoring coronary laser procedures in the United States before the technology became commercially available in India.
Performing and proctoring India’s first reported coronary laser atherectomy after that launch in 2021 was therefore a memorable moment for me.
But after years of working with the technology, my view of it is actually quite simple.
Laser is not magic.
It is a very useful tool for particular problems.
Sometimes the guidewire crosses but the balloon will not.
Sometimes an old stent refuses to expand.
Sometimes conventional equipment reaches its limit.
That is when experience with different techniques matters.
For me, that is the interesting part of complex PCI-not using an exotic device, but understanding why the procedure has become stuck and what is most likely to get it moving again safely.
Selected References
- Excimer Laser Coronary Atherectomy for Uncrossable Coronary Lesions. Catheterization and Cardiovascular Interventions.
- Excimer Laser Atherectomy in Percutaneous Coronary Intervention: A Contemporary Review. Cardiovascular Revascularization Medicine.
- Excimer Laser Coronary Angioplasty in Coronary Lesions: Use and Safety From the NCDR/CATH PCI Registry. Circulation: Cardiovascular Interventions.
- SCAI Expert Consensus Statement on the Management of Calcified Coronary Lesions.
This article is intended for education and does not replace individualized medical advice. Decisions about coronary angioplasty, CTO intervention, atherectomy or laser treatment need to take into account the patient’s symptoms, coronary anatomy, medical history and alternative treatment options.
