The Princeton Longevity Center Medical News
A New Genetic Test That May
Revolutionize the Treatment of Coronary Disease
By: David A Fein, MD
We have been hearing for years that genetic testing holds the potential to revolutionize medicine. Our genes may hold clues to our risk of developing many of the chronic diseases that can prevent from enjoying the years to come. While numerous genetic tests already exist, their use has been limited. There simply has not been much use for a test that tells you that your risk of eventually developing a particular disease is 35%, compared with an overall risk in the general population of 5%. While your risk is certainly higher, that still does not mean you will get the disease. Genetic testing is even more limited in value when we don’t have any treatments available to prevent the disease, such as is the case with Alzheimer’s Disease.
One area where genetic testing is starting to show results is in predicting responses to drug treatments that allow us to individually tailor your care. Three studies recently published in the Journal of the American College of Cardiology highlighted the role of a new gene test in predicting who is likely to respond to statins, the class of medication that includes Lipitor and Crestor for cholesterol lowering. This test may allow us to determine in advance who will lower their heart attack risk with these medications and who will need to consider other treatment options.
Statins are the most effective medications that we have for treating coronary artery disease. But these medications are still woefully inadequate. Even though they are dramatically effective in lowering cholesterol levels in almost everyone, most people don’t realize that statins generally lower the risk of a heart attack by only about 30%.
Even worse, the degree of cholesterol lowering does not appear to predict whether you will be in the 30% who avoid a heart attack or are in the 70% who end up getting little or no benefit from taking the medication.
In the St Francis Heart Study researchers followed the progression of coronary artery disease using heart scans to measure the Coronary Calcium Score. They found that nearly 95% of the heart attacks occurred in those patients who were on medication but continued to have an increase of more than 15% per year in their Coronary Calcium Score. In the group where the treatment succeeded in slowing the progression of the plaque there were almost no heart attacks. But the average cholesterol level was the same between the two groups. Just lowering cholesterol with medication did not explain why one group did so much better than the other.
Research has indicated for years that the cholesterol lowering effects of statins may turn out to be much less important than other effects the medications have within the blood vessel and the plaque itself. Statins may help to reduce inflammation in the arterial wall or prevent the movement of cholesterol into the plaque. Patients who get these effects may get much more protection from heart attacks with statins than the patients who are genetically not programmed to respond to these effects.
The new research shows that a particular gene, known as KIF6, appears to predict which patients are likely to benefit from statins. The gene also appears to predict who is at higher risk for a heart attack.
About 60% of the population has a variation of this gene that puts them at high risk for heart attacks. In one of the studies, carriers of the KIF6 gene variant were 24% more likely to develop coronary artery disease and 34% more likely to have a heart attack. In another study, the increase in risk for both coronary disease and heart attacks with this form of the gene was more than 50%.
Even more importantly, the research found that carriers of the KIF6 genetic variant had more than 8 times the reduction in heart risk from taking a statin compared with those who did not have this version of the gene.
The difference between the groups was unrelated to their levels of cholesterol, LDL, triglyceride or C-reactive protein. In other words, statin medication lowered the cholesterol equally well in both groups but those with the KIF6 gene variant had a significantly greater benefit from taking the statin.
While more research is needed, these results may indicate that we can start to identify in advance which patients are likely to lower their heart attack risk with statins and which patients need to be on other therapies. Those patients who do not have the KIF6 variant may need to be more aggressive about reducing other risk factors and improving their nutrition and fitness. Combining their statins with other medications, such as high dose Niacin and Omega 3 supplements, may also be important.
The KIF6 test requires only a simple swab of the inside of the cheek. KIF6 testing is now available as part of our Advanced Cardiac Testing option in our Comprehensive Exams. The KIF6 test can be used to personalize your treatment plan.
Patients with significant amounts of plaque on their heart scans and elevated cardiac risk may be able to use the KIF6 results to guide their decision-making as to whether they are likely to see a good response to statin therapy or would benefit from additional attention to complementary therapies.
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