What gives? How can someone with high blood cholesterol levels for 30+ years end up with clean arteries, if indeed there is any causation between blood cholesterol levels and plaque accumulation. ... Perhaps actual blood cholesterol levels have no cause of heart disease on their own a-priori. And, if any of these crazy hypotheses are true, then how can a health system prescribe drugs like statins so casually and routinely to anyone with cholesterol over 230? This is particularly true, when the long term side effects of such drugs must still be unknown.
Lots of questions -- some scientific, some health-plan political... But mainly I am looking for just straight talk on this whole cholesterol/heart disease issue.
You ask a lot of good questions. Let me paraphrase them for ease of presentation.
1. How do statins help in heart disease - through lowering the cholesterol level or some other mechanism?
It's not clear - this is one of those topics where the pendulum of the literature swings back and forth, and I can't say that I've followed every swing. Some hold that statins lower cholesterol, cholesterol causes heart disease, and that's it (though all the details of what the worst cholesterol particles actually are, and how they work their deadly magic, are yet to be fully worked out). Others think that statins are "pleotropic" - i.e. they work in multiple ways, e.g. by reducing inflammation.
2. How could you have high cholesterol and still have clean coronaries?
It's quite possible. I would imagine pretty common. That's why one of the biggest statin-related controversies hasn't really hit the lay press yet. It's all about when to give the medicines. Should everyone be on a statin if their cholesterol is above a certain level ("treat to target," or what I think of as the "statin in the water" approach), or should a statin be used only if a patient's risk of coronary artery disease is above a certain level ("tailored treatment")? A recent study in the Annals of Internal Medicine supports the latter, but no one really does this yet since the guidelines of the major doctor groups favor the former.
3. How do I know if I need to take medicine for cholesterol?
One way to think of it is this: statins lead to a reduced risk of coronary artery disease. Great. But this only matters really if your ABSOLUTE RISK, before statins, is something that you, or your doctor, are concerned about. If your 10-year risk of heart disease is 1%, and the statin reduces it to 0.1%, that's a 90% risk reduction, but maybe you don't care about a 1% risk. (I might not.) One way to calculate your risk is the Framingham risk calculator.
4, Do clean coronary arteries on a coronary CT scan (i.e. a low calcium score) mean I can't have blockages in the heart arteries?
No.
Refreshing! Looking forward to when we know all the answers....
ReplyDeleteexcellent post Zack! A couple of comments I would add for your readers:
ReplyDelete1. The role of statins in cardiovascular disease has been shown to be rather beneficial depending upon the context- be it in those with disease of coronary arteries and their short-term survival, diabetic patients without any history of heart attacks, or even in certain stroke patients (in helping to prevent recurrent stroke). The use of these drugs in patients with other types of cardiovascular disease such as those with peripheral arterial disease (commonly known by the misnomer "leg claudication") has yet to be fully established.
What is indeed interesting, as Zack mentions, is that while statin use has been shown to lower cholesterol it doesn't clearly seem to be the lowered cholesterol itself through which the benefits are conferred. Statins effect the body through many different ways, and most importantly have been shown to ameliorate, and in some instances even reverse the abnormal function of arteries in those who are predisposed to cardiovascular disease. We even have some exciting new data suggesting that statin use can make the "cholesterol plaques" lining the arteries more "stable" by altering their biomolecular composition... this means that the plaques themselves are less likely to progress or rupture and cause heart attacks and strokes.
2. The "tailored treatment" approach is starting to become more common... although the tests that we can use to help estimate your risk of having a heart attack or stroke are becoming more widespread and accessible (such coronary CT/calcium score and carotid MRI or ultrasound), I worry whether this tailored approach will in turn become a much more expensive way to decide whether or not to treat and at what dose. Will this added cost pay off in the long run? What about for people who don't have access to these tests or can't afford them?
-aj