By John D. McBrayer, M.D.
Early detection of coronary artery disease is a significant problem. One third of deaths aBer 35 are secondary to cardiovascular disease. One half of middle aged men and one third of middle aged women will develop coronary artery disease. Currently our ability to detect early disease is limited. By the time symptoms occur there is usually 70% obstruction of the coronary artery. Data from autopsies on Korean War casualties indicate initial signs of development of coronary plaque in the early 20’s of age. Theoretically it would seem appropriate to begin prevention therapy as soon as possible but who should get it? Obviously, the patients with known vascular disease and equivalents such as diabetes would need this therapy. Those without established disease need an estimate of their risk.
Prevention therapy does require medications and current thinking is to use prognostic risk factors to predict probability of disease development and then gauge aggressiveness of treatment. Long term medications have their own risks and side effects. Treatment benefit would need to outweigh risks. Currently the Framingham risk score is the most common calculation of risk of cardiovascular mortality. The results are categorized to low, medium , and high 10 year risk. If the estimate is made at a young age the lifetime risk could still be high. This calculation is dependent on age, gender, cholesterol, HDL cholesterol, hypertension and smoking . These factors are felt to be responsible for 50% of coronary disease. Generally aggressive medical therapy is felt to be necessary in the high risk group and probably effective in the moderate risk group. This therapy is usually blood pressure control, low dose aspirin and statins to lower cholesterol. Statin therapy has a variety of concerns including muscle weakness, liver toxicity, and questionable psychotropic effects. Generally these medications are considered safe in the medical field but there is a fair amount of resistance to the idea in our culture.
This is where coronary calcium scoring comes into play. As cholesterol is deposited in the luminal lining of the coronary arteries it induces inflammation. This leads to calcium deposition in microscopic amounts. The total calcium deposited seems to be related to the total volume of plaque but not necessarily to the level of obstruction in the artery. This can be visualized with rapid CT scanning. The volume “score” correlates with risk of cardiovascular mortality in the future. It adds information for prognostication of disease. An example would be if the patient has only moderate risk by the Framingham score but calcium score is high then aggressive medication therapy would be indicated. If the score was low then perhaps medical therapy would be less necessary.
The test is a simple Computerized Tomographic scan using about 1/3 of radiation for usual CT scan. There is no IV contrast or sedation required. Image time is less than 1 minute. It is not covered by insurance and generally costs $50-100, depending on where it is done. My experience is that visualization of the problem adds significantly to patient willingness to accept treatment .
