Posts Tagged ‘Atherosclerosis’
What Does a Calcium Score Mean?
Technology now aids cardiologists in making decisions as to which patients may or may not have coronary artery disease. In the past, this was quite difficult and led to many needless tests and the repetition of tests that provided no value to patient care. As the readers of my blogs know, many pieces of a patients illness can be placed into risk calculators and then a risk can be assigned that will help cardiologists in decision making. The Framingham calculator is one such tool. The higher the score the more risk and the more concern with a work up. There is no one right way to do it.
It has become more and more difficult to do this without substantial interference from insurance companies. Many now require pre authorization before any work up and this includes cardiac cath. They are essentially practicing the medicine of NO. It is very complicated and time consuming to accomplish any sort of work up and this is likely to be the tip of the iceberg.
Now an article in the J AM COLL Cardiol 2010 55:1110-1117 has been published discussing the technique of calcium scoring and its usefulness in both determining who is at risk and when they would need to be tested again. As it is claimed in the article “what is the warranty for a negative score?”
When atherosclerosis starts in an artery, the artery first gets larger in a process known as positive remodeling. Only when this process stops does the obstructive phase of atherosclerosis begin so in general angina caused by blocked arteries is a very late phenomenon in the illness. Calcium is deposited and can be visualized in coronaries early on and this is what is seen on the CT scans. Using high speed scanners and one pass of the gantry a score can be assigned from zero to over a 1000. The higher the score
The more risk there is. If your score is zero, then you are likely to remain free of coronary events for four years according to the article.
This kind of work is useful for both determining the burden of illness and the limiting of downstream tests in an individual patient. It should in theory allow us to control costs in a meaningful way. That is if the insurance companies let us.
And Away Goes Trouble Down the Drain…
In the middle ages, Alchemists dreamed of transmuting coal into gold. In much the same ways Cardiologists have dreamed of a substance that would remove plaque that had already formed akin to Drano removing scale and rust from pipes. The best we have so far is statins like Lipitor and Crestor, which has been shown to diminish plaque burden by Intravascular Ultrasound or as it is known IVUS. The mechanism by which statins work is believed to be more reorganization of plaque than the removal of material.
In June 2003 a study was published in JAMA 2003, which electrified the field of cardiology. Here was the promise fulfilled, a substance that would remove plaque. That substance is ApoA-1 Milano now called ETC-216 as it was purchased by Esperion and renamed.
Over the time period November2001 and March 2003, 123 participated in the study. All had ACS- acute coronary syndrome and I have blogged about this syndrome frequently. They were randomized into three groups’ placebo, low-dose and high-dose, and underwent once a week infusions of Apo for five weeks. IVUS was done before and after, and then analyzed to see the differences in plaque volume and composition.
The mean percent decrease was 1.06% in the treatment group and an increase of .14% in the control group. The absolute reduction in atheroma volume was 4.2% and this carried a p value of <.001. The lower the p value the more significant thus this is a very significant result.
In the short span of five weeks, atherosclerotic coronary lesions were shown to reverse. Further, the dose of ApoA-1 did not matter. Both the low-dose and high-dose had the same effect and it is believed that the mechanism of action is the stimulation of reverse cholesterol transport.
That’s were it ended. Since 2003 no further work was done because Esperion was purchased by Pfizer and Pfizer was probably doing that to “bury” it because it was working on its blockbuster oral drug torcetrapib. That failed and Pfizer said adios to cardiac research.
The Medicines Company has a track record of delivering new drugs to market that have not been adequately studied. Let’s hope that the work will now be started and finished to show whether this compound is the beginning of a new treatment strategy for atherosclerosis. I will keep you informed.
The Benefits of Statins
Statins, which if you haven’t guessed by now are one of my favorite topics and are making news again! Two new recently published studies continue to show the tremendous value of these drugs both before you develop the disease of atherosclerosis and after it’s treatment.
A meta-analysis is a process were multiple studies are analyzed together to increase the ability to define value to drugs or medical process. This process has some statistical problems as studies are often enrolled in different ways but in general the technique is regarded as useful to inform us as physicians how to best treat our patients.
Dr Jasper Brugts recently published such a study in the British Medical Journal BMJ 2009; 338:b2376. Titled “The benefits of statins in people without established cardiovascular disease but with cardiovascular risk factors” the analysis showed that statins cut deaths by 12%, coronary events by 30% and cardiovascular events by 19%.
This study looked at ten trials including the recently blogged Jupiter trial ( June 15, 2009). A total of 70,388 subjects without cardiovascular disease but with risk factors for its development were included in this analysis. This effect was seen regardless of age, gender, or diabetic status. It is also important to realize that this effect is in addition to diet and exercise and represents “real world” use.
It is important to discuss with your physicians the use of statins in your case. Targets are LDL < 100. If you already have coronary artery disease the target LDL is < 70. These targets are easily obtained in most cases with today’s drugs. It is not the amount of drug you take it is the drugs measured effect on you. In general, taking more of the drug tends to lead to greater clinical benefit. There is an extremely wide variability to these drugs so comparing your dose to your friend’s dose is of no value. Also, these drugs are everyday drugs and taking them every other day is not advised.
Next…using statins before angioplasty.
Atherosclerosis: A Lifelong Enemy
In my last blog I reviewed some basic information about statin use for the treatment of atherosclerotic disease. Atherosclerosis manifests itself in many forms. In the heart it manifests itself as angina and myocardial infarction; in the brain, as strokes — either minor or major; in the legs, it manifests as painful calves or buttocks when you walk. We call this claudication. In the abdomen, as abdominal aneurysms, which rupture and can cause a quick death. In fact, most deaths in the United States are due to this process; in all, over one million deaths a year.
At least once a week I hear the phrase “but my cholesterol has always been good.” Unfortunately, as physicians, we do not have a practical way to determine the differences between two people who have the same cholesterol and different outcomes. Cholesterol is a combination of the components triglycerides, LDL cholesterol and HDL cholesterol. These three components are in constant motion with triglyceride being added to LDL to form HDL. Our livers manufacture cholesterol because it is a basic building block of our body. We, in general, only eat 10% of our total cholesterol level — so diet alone is never enough to treat documented atherosclerosis.
Since the Vietnam War, we have known that atherosclerosis starts at a very early age. Most of the autopsies done at that time showed some atherosclerosis and in some individuals it was quite advanced. Once you have atherosclerosis you can not get rid of the damage. Early treatment is warranted and now, in some instances, we have started treating children.
Next: The HPS and the dawn of a new paradigm.
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