Cholesterol has been at the center of much research for a long time – ever since it was identified that stroke and heart attacks result from a process happening in blood vessels called atherosclerosis.
What is Atherosclerosis?
Atherosclerosis simply means hardening of the blood vessel walls; what it entails is a progressive deposition of cholesterol in specific regions of the vessel wall with subsequent changes, all of which lead to formation of ‘plaques’ in the vessels walls. These plaques undergo further changes and can become unstable, rupture, and form clots or thrombus (plural, thrombi) on their surfaces.
What is Embolism?
The clots on the surfaces of these plaques can block the blood vessel or lead to “embolism” in which the clot breaks up into smaller pieces of “emboli”, and these smaller pieces then migrate along the blood stream. A shower of such emboli can lodge in a smaller blood vessel, blocking it, and leading to damage to the underlying tissue ( a kind of damage called ischemic infarct).
This whole process of cholesterol deposition to plaque formation to embolism may take many years – so the time course for prevention can also work over many years. Prevention strategies are also aimed at different levels.
People who have diabetes and high blood pressure are more prone to develop the negative consequences of high cholesterol levels in the blood. Uncontrolled diabetes is especially potent in increasing the risk of heart disease and stroke through this mechanism.
One strategy to reduce the risk of stroke or heart disease is to lower the levels of cholesterol in the blood. This is not such a straight – forward goal as it may be thought.
Cholesterol does not enter or leave the body so easily. In fact, Cholesterol is entirely synthesized in the body – inside the liver, in fact. It travels around in the blood stream using different vehicles, called lipoproteins. We know these as ‘good cholesterol’ which is HDL (or High Density Lipoprotein), ‘bad cholesterol’ , which is LDL (or Low Density Lipoprotein), and so on. What we absorb from the diet are in fact the fatty acids which are used to synthesize cholesterol.
Beyond this, things in the Cholesterol World start getting murkier. Why isn’t it such a simple matter to reduce the cholesterol level in the blood? Why did a new Expert Panel have to come and change the guidelines and completely upset the apple cart?
Existing guidelines for lowering cholesterol
In the ATP III report, which published the existing guidelines for cholesterol control, lipid lowering was based on targets such as treat – to cholesterol target, lower cholesterol is better, and risk – based treatment approaches, etc. Over the last few decades, these guidelines spawned the use of many different drugs to lower cholesterol in people who were barely at risk for heart attack or stroke. If somebody had chest pain, bang, he had a Lipid profile done; if his LDL was over a 100 mg/dL, Bang! he was prescribed a statin. Even women in their thirties (pre-menopausal), who were always traditionally considered to be protected from heart disease were evaluated for heart disease.
It became fashionable for men and women in their twenties and thirties to undergo TMTs and Lipid Profile evaluations and for everyone to be on lipid lowering therapies. Based on the previous guidelines, an army of clinicians had broadened the scope of the guidelines to included more and more patients from diverse ethnic backgrounds and with minimal risk factor profiling to be treated with lipid lowering drugs.
Industry – Driven
A large part of this was industry – driven. The result of this was that a majority of results seen in trials was not replicated in real life. The Expert Panel was therefore constituted to exclude certain levels of evidence not considered robust enough, and to frame new guidelines based on only the best evidence, which basically means Randomized Controlled Trials (RCTs).
RCTs are limited in number at the moment, owing to the fact that they are difficult to design and expensive to conduct. The new set of guidelines are not comprehensive, nor do they entirely replace the older set of guidelines.
So What’s new in the Guideline?
Here is a link to the pdf to the Full Guideline on Circulation
- The Expert Panel recommended that Statins should be used in 4 identified “Benefit Groups” (see below)
- They do not support specific LDL – Cholesterol treatment targets
- They also do not support specific HDL – Cholesterol treatment targets
- For the “Benefit Groups” Statin therapy should be used in appropriate intensity/dose
- Non – statin therapy not recommended
- They recommend a new Pooled Cohort Equation to estimate 10 year risk for heart disease or stroke
The 4 “Benefit Groups” identified by the Expert Panel are:
- Those with clinical Atherosclerotic Cardiovascular disease i. e., those who had a heart attack past or present, or unstable/stable angina, those having undergone a coronary revascularization procedure such as stenting or bypass, those who had a stroke or TIA, or those with peripheral vascular disease
- Those whose LDL – C levels are >= 190 mg/dL
- Diabetes aged 40 – 75 years, with LDL – C between 70 – 189 mg/dL even without clinical evidence of Atherosclerotic Cardiovascular Disease i.e., never had heart attack or stroke
- Those with an estimated risk of heart attack/stroke/peripheral vascular disease using the new Pooled Cohort Equation > 7.5% (even if they don’t have Diabetes and elevated LDL – C).
The factors considered in this Risk Estimator are: Gender, Age, Race, Total Cholesterol, HDL – C, Systolic BP, Treatment for BP, Diabetes, and (Whether or not a) Smoker.
Submit your information using the form below, and I will get back to you with your Heart Attack and Stroke Risk Estimation using the Pooled Cohort Equation created by the Expert Panel.
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