So, it seems simple, you’ve been found to have carotid artery disease, you have surgery to “fix it” and reduce your future stroke risk, right?
Well, you guessed it, it’s not that easy.
First, some facts about carotid artery disease and stroke:
Each carotid endarterectomy surgery costs about $15,000.
When you undergo surgery, there is a surgical risk (of stroke or death) which you pay up front, in exchange for a cumulative annual stroke rate reduction (%/yr) for the remainder of your life.
A good analogy is taking out a mortgage. Doing surgery can be compared to paying points on your new mortgage to lower the future interest rate. Your more likely to do it for a 20y that for a 5y mortgage.
Whether the benefits of surgery exceed the risk, whether it is worth paying points on your mortgage, and will depend on:
1. The actual risk of surgical complications at your center
2. Your age (i.e. future life expectancy),
3. The degree of carotid stenosis,
4. Most importantly, if you have had a TIA or stroke in the vascular territory of the affected artery within the previous 6-months – referred to as a symptomatic carotid stenosis.
FOR A SYMPTOMATIC CAROTID STENOSIS ≥70%
Surgery will reduce the risk of stroke from 26 to 9% over 2yrs
That’s a “relative risk reduction of 60%”
You have to treat 6 pts to prevent 1 stroke/2yr
Or, treat 2.4 pts to prevent 1 stroke/5yrs
FOR A SYMPTOMATIC CAROTID STENOSIS 50-70%
Surgery will reduce the risk of stroke from 22 to 16% over 5 yrs
That’s a “relative risk reduction of 30%”
You have to treat 16 pts to prevent 1 stroke/5yrs
FOR AN ASYMPTOMATIC CAROTID STENOSIS ≥ 60%
Surgery will reduce the Risk of stroke from 10 to 5% over 5yr
That’s a “relative risk reduction of 50%”
But, you have to treat 20 pts to prevent 1 stroke/5yrs
FOR AN ASYMPTOMATIC CAROTID STENOSIS <60%
There is no benefit from surgery
The above data is abstracted from the NASCET and ACAS studies, and are based on a surgical complication rate of <6% for symptomatic and <3% for asymptmatic cases. Complication rates can be as high as 10% at some centers. Click here to find your hospital, and look up the complication rate from carotid surgery.
All patients with symptomatic carotid stenoses >70% are probably going to benefit from surgery, even more so if they get to surgery within 2 weeks of their TIA or stroke.
Most patients with symptomatic carotid stenoses in the 50-70% range will benefit from surgery, if it is done at a center where the surgical complication rate is <6%, and they have a life expectancy of >5 years.
The benefits of surgery for an asymptomatic carotid stenosis identified on a routine screening study are much less certain. You can bet the surgeon will tell you that he/she can reduce your future stroke risk by 50%, but all they are really doing is increasing your chance of not having a stroke from 90 to 95% over the next 5 years, so if you are in your 80s or at a center where the complication rate from surgery is >5%, you’re probably not going to break even, and would do better to stick with medical therapy.
Remember to ask these questions before signing up for surgery.