Old but still gold—why coiling remains a vital tool for treating intracranial aneurysms


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Alberto Nania

Alberto Nania (National Health Service [NHS] Lothian, Edinburgh, UK) speaks to NeuroNews to outline how, despite the rapid proliferation of new technologies and clinical data in the interventional neuroradiology (INR) space over the past 20 years, coil embolisation remains a fundamental tool in the treatment of intracranial aneurysms.

“If you think about coiling, and you think about the ISAT trial, it is the foundation of INR practice as far as haemorrhagic stroke and aneurysm treatment is concerned,” Nania posits. “So, it has passed the test of time—it has been around for decades, its safety profile has improved since the early 2000s, because the technology has changed, and I think its efficacy is better as the materials have also changed.”

While coil embolisation may be a cornerstone of the specialty of INR itself, rapid advancements over the past two decades have given rise to other devices and approaches used in the treatment of intracranial aneurysms. Prominent examples include flow-diverting stents and intrasaccular technologies—both of which have come along more recently, and thus may be considered more innovative and ‘sexier’ than coiling, according to Nania.

“Is coiling still the gold standard? I think, for most aneurysms, it is,” he continues. “Compared to 15–20 years ago, the horizons of INR treatment have broadened quite significantly. There are a lot more indications for which we can offer endovascular treatments and, with that in mind, there are a number of circumstances in which coiling is not the gold standard.”

Nania feels however that, far from coiling being ‘replaced’ as the go-to approach, this is simply a case of INR expanding and enabling a greater variety of aneurysm cases to be treated. An example he highlights is a giant symptomatic cavernous aneurysm; “almost everyone would treat that with a flow-diverting stent now, but that is because we are [talking about] something that could not be treated in the past”, he avers.

“So, for most cases, it does remain the gold standard, and I think it really is the basis of aneurysm treatment,” Nania goes on. “If you think about ruptured aneurysms in particular, in most cases—if the neck of the aneurysm will allow you to coil—I think you should coil. “The concept and the strategy have been around for such a long time, and we know that it works; it is proven to be effective [and safe]. And, overall, it is probably more widely applicable than intrasaccular device or flow diverter placement too, because you can use a smaller, ‘softer’ microcatheter and go more distal, overcoming tortuosity-related problems with [things like] intermediate catheters.”

Nania attributes the continued relevance of coiling, in no small part, to the work done by neurovascular companies to advance the microcatheters, the guidewires, and the coils themselves, allowing an established technique to “reach new levels”, such as in the treatment of very distal aneurysms. Medtronic and others in the INR space have “invested massively” to make these devices “a lot easier to use, and a lot better”, he adds. And, discussing the wider role of coiling in the arsenal of an interventional neuroradiologist, he describes it as a “key skill”, and one that can be “very rewarding”.

“It does have a learning curve,” Nania notes. “I do not coil an aneurysm the same way I did four or five years ago, and in another five years’ time I will hopefully get even better. So, there is a lot of reward in learning a skill that you can keep practising. There are limitations to what coiling can do, and those have to be remembered—wide-neck bifurcation aneurysms, blisters, giants, and so on—so nowadays it has to be complemented by a number of other devices. But, it is still a pillar of the INR armamentarium, in my view.”

To coil or not to coil?

Laying out his own paradigm for when to use coiling and, equally, when an alternative approach may be preferrable, Nania says that ‘ruptured’ and ‘unruptured’ are the two main categories when it comes to intracranial aneurysms. In ruptured cases, he believes that coiling is the way to go, provided the aneurysm is big enough to hold a coil (>1mm). However, patients with very wide-necked aneurysms, or high-grade subarachnoid haemorrhage, are likely to require a “speedier procedure” and, as such, intrasaccular devices can play a “big role” in these cases.

“For ruptured cases, by and large, the priority is to avoid more complex situations, such as with double microcatheters; apply the principle of ‘keeping it simple’… and coil as often as you can,” Nania states. “In the unruptured cases, you have a lot more tools to play with—you may complement [coiling] with a stent, or a flow diverter, and for wide-neck aneurysms you are obviously spoilt for choice with complex treatments like Y-stenting, stent-coiling, flow diversion and the intrasaccular devices.”

Another point raised by Nania is that of cost, which is “very important” for certain healthcare systems. Here, the example he puts forward is that of a small aneurysm (~4mm) that can be treated with either coiling or an intrasaccular device, claiming that it will inevitably be “much cheaper” to coil.

“To contextualise this by looking at my own practice in Edinburgh,” he continues, “last year, we treated almost 280 aneurysms in total—between ruptured and unruptured. In acute cases, coil usage was at almost 80% and, in elective cases, it was almost 50%. So, I think it is still fundamental in both situations.”

Ballooning remains relevant

Paraphrasing one of the physicians he trained under, Nania asserts that ballooning is and always has been a “core technique”, not just within aneurysm coiling, but as a means for increasing safety and reducing the likelihood of complications in other procedures like mechanical thrombectomies.

“In aneurysm coiling, it has to be recognised that ballooning increases the complexity of the procedure a little bit because you have a double microcatheter; you have to worry slightly more about your support, your access and your sizes, and it tends to lengthen the duration of the procedure a little,” he says. “But, it does allow you to tackle aneurysms that, due to their morphology or configuration, simply could not be coiled otherwise. It massively increases the range of capabilities of your coiling procedure.”

On a technical level, the introduction of a balloon can support the operator in cases with challenging anatomies. As Nania adds, “you can trust the balloon to protect particular branches, and to overcome the difficulties of projection”.

“So, it is great in terms of its enhanced capabilities we used in conjunction with coils,” he claims. “Perhaps, if you look at INR practice in general, [ballooning] has lost some ground regarding frequency of use because there are so many other options now—for example, in bifurcation aneurysms, there are now intrasaccular devices that have taken out a lot of the work that used to be done via balloon-assisted coiling. But, it is still core, and it is still essential to learn and to master as a technique.”

What does the future hold?

“It is very hard to predict but, the way I see it, coiling will remain a huge stakeholder, at least over the next 5–10 years,” Nania says. “Its role might change in the sense of being complemented by a lot of other devices but, if anything, I see these devices complementing coiling during the same procedure rather than taking cases away. In recent years, other devices have been coming to the market to address inherent shortcomings of the technique itself, but I see very few devices that can completely replace coiling, and there will still be space for coiling in the future for sure.”

According to Nania, the main message here—particularly for newer generations of interventional neuroradiologists, who “may be distracted” by more novel technologies and approaches—is that coiling remains “a pillar of our specialty”.

“It needs practice, and it needs time dedicated to it, but it has incredible rewards,” Nania concludes. “It is proven to be effective and, alongside mechanical thrombectomy, it remains a key therapy that [younger interventional neuroradiologists] should learn before digging too deep into flow diverters or intrasacculars.”


DISCLAIMER: The data and content included in this presentation express only the clinical perspective of the presenter. They are completely independent and do not necessarily reflect the opinions of Medtronic.


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