Monday, July 09, 2012


The last week, some of my patients had been asking about the "Drug Eluting Balloons". I think it was featured in one of the local daily, and so they were asking. I thought that I should use the opportunity to write up briefly on it.
The journey began at the Schering lab in Germany back in 1999. The issue that interventional cardiologist were struggling then was the issue of re-stenosis ( re-narrowing ) following balloon angioplasty and bare metal stents. Two German chemist, Speck and Scheller, who were experts at radio-contrast dyes, thought they one idea will be to coat a balloon with a anti-proliferative drug andplace the balloon against the wall of the atherosclerotic plaque ( as shown in the diagram ), and allow the drug to diffuse passively into the endothelial lining of the artery wall, so that it can exert its anti-prolifeartive effects and reduce re-narrowing. It was a good idea, and being experts with knowledge of radio-contrast dyes and their chemical properties, they used the dye base to retain the drug so that it will not easily be washed away. They then convince some peripheral interventionist to try it in treating peripheral vascular disease. It seemed to be safe and it work better than plain old balloon angioplasty. From the peripheral limbs, they began to use it in human coronary arteries. BBruan was the first company to make the Drug Coated Balloon commercially available and got their CE mark in 2009.
The concept was simple. Stick the drug ( anti-proliferative ) against the wall using the drug coated balloon for 60 seconds, allow the drug to stick to the vessel wall and act to reduce excessive scar tissue formation ( the cause for re-narrowing ). The trick is to find the right carrier coating to keep the drug on the balloon and wall long enough ( not too short and not too long ). For the moment, the most popular drug used is paclitaxel, because it is lipophilic. Sirolimus ( the better drug used in drug coated stents ) is hydrophilic and so we have to develop a technology to prevent it being wash away too fast. I believe that that technology is now available, and the first generation -limus eluting balloon ( I do not know the drug name ) is beginning clinical trials.
When this idea was first introduced to me, back in the early 2000, I was sceptical that keeping a balloon opposed to the vessel wall for 60 seconds could elude enough drug ( considering the washout of the drug ) to influence re-narrowing. Time has proven me wrong. It does work, but not as well as drug coated stents. So maybe I am partly right.
Currently there are  at least 5  companies manufacturing drug coated balloons, with their difference carrier drug coatings and different balloons to achieve their results. B Bruan was the market leader for a while with their Sequent Please series, EuroCor with their Dior balloon now in their second generation, Biotronik with their Pantera balloon and Medtronic with their Falcon balloons. Each of these balloons have their strength and weakness. All these balloons use paclitaxel as the drug. On the basis of pharmaco-kinetics and early results, it looks like the Falcon balloon hold an advantage and early results ( 2 years ) seem to suggest that. But it is really to early to tell.
Of course, without a stent platform, there is really no issue with stent thrombosis and dual anti-platelet therapy need be given as in bare metal stent treatment. I suppose that is one great advantage. However, although Drug Coated balloon has lower re-narrowing rates than bare metal stents and plain old balloon angioplasty, their re-narrowing rates are still significantly higher than those of drug coated stents.
Currently, I use the drug coated balloons almost exclusively for re-narrowing of a stent, either bare metal or drug coated stents ( so rare nowadays ).  In this context, it seems to work quite well.
There is much more work being done using the drug coated balloons in peripheral limb salvage and peripheral vascular disease.
However, I am anxiously awaiting the arrival of a -limus coated balloon as I believe that the -limus drug is better for reducing re-narrowing. Looks like at the end of the day, drug coated balloons will only have niche use, and that niche seems to be "in-stent restenosis ".

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