Heart Attack Prevention: Coronary Calcium Scans Better Than CRP
The use of a coronary calcium scan is emerging as the most effective way to prevent heart attack and stoke in people who show no evidence of high cholesterol levels.
These findings, presented in the journal The Lancet, could help guide doctors in prescribing statin medications more accurately to patients.
Statin are a class of medications that have been historically prescribed for patients with high blood cholesterol to help prevent cardiovascular disease. However, in a large 2006 trial called JUPITER, researchers found that stain medications could actually benefit patients who fall into a “gray-zone” category of heart attack and stroke risk. These patients have normal levels of cholesterol, but high levels of an inflammation maker called C-reactive protein (CRP).
The problem is that there are roughly 6 million people in the United States who meet the criteria for this so-called gray category. Some doctors questioned whether prescribing statins for all of these patients was really beneficial enough to have a significant impact on reducing heart attacks and stroke. Statin therapy can produce uncomfortable side effects and cause serious complications which need to be considered when choosing this course of therapy.
As a part of a NIH-funded study, researchers sought to further identify who were really at high risk and would benefit from statin medications as well as those who likely wouldn’t benefit at all. They followed 2,083 people for over 6 years who met all of the same criteria for the previous JUPITER study.
Dr. Michael J. Blah, a cardiology fellow at John Hopkins University School of Medicine and lead author on the study, and his colleagues compared the use of statin medications in patients with high levels of CRP versus those who had high levels of calcium in their coronary arteries as seen on a cardiac CT scan.
"This was a direct comparison to see which patients with a normal LDL level of less than 130 mg/dL would have the greater risk of having a heart attack or stroke—those with evidence of calcium in coronary arteries, as determined on a cardiac CT test, or those with high levels of C-reactive protein, which is measured in blood and is an indicator of inflammation somewhere in the body," said Dr. Blaha.
In the results of the study the researchers found that a staggering 95% of the heart attacks, strokes, and heart-related deaths occurred in those patients who had calcium present in their coronary arteries. Furthermore, 13.4% of those with the highest levels of calcium (scores of 100 or more) had a heart attack during the study compared to only 2% of those with high a CRP and no calcium buildup.
The researchers were able to conclude that the coronary calcium test was a more accurate predictor of heart attacks and other cardiovascular events than CRP and therefore could be a better guide in determining which patients to treat with statin medications.
"While not everyone needs a calcium scoring test," Blaha said, "we believe looking for calcification in coronary vessels in certain patients makes sense in order to predict who may benefit from statin therapy because the test gets right to the heart of the disease we want to treat."
However, the study authors also point out that statin therapy, which is a life-long therapy, should not be considered a replacement for other heart attack reducing measures such as diet and exercise.