CT Scan for Heart Risk Splits Doctors

A study suggests a benefit for 33.5 million Americans; not all are convinced.

Aug. 22, 2012— -- For hundreds of thousands of Americans, the first sign of heart disease is when their heart stops.

It's a situation that has cardiologists constantly searching for better ways to detect heart problems sooner. On Tuesday, a study published in the Journal of the American Medical Association suggested that a test using a CT scan could lead to answers for many of the 33.5 million Americans deemed to be at intermediate risk of heart problems.

Yet the scan is not without its drawbacks -- a fact that has some doctors skeptical as to whether this test should be offered more widely.

The test -- known as a coronary artery calcium score, or CAC -- is found by evaluating the amount of calcium in blood vessels around the heart. Doctors accomplish through a CT scan of the chest.

In the new study, a team led by Dr. Joseph Yeboah, assistant professor of internal medicine-cardiology at Wake Forest Baptist Medical Center, found that this test was the most effective of the six different methods to determine someone's risk of future heart problems if they happened to be classified as having an "intermediate" risk of heart disease.

Doctors can tell patients whether they are at high, low or intermediate risk of developing heart disease by using what is known as the Framingham score -- a tool that looks at age, cholesterol, blood pressure, smoking history and gender. A high-risk patient will likely be treated more aggressively with blood pressure and cholesterol medications than their low-risk counterparts.

But while this approach works well when it comes to high or low risk patients, for the 16 percent of Americans in the intermediate risk category the lines are fuzzier as to when they should start taking these medications.

While the CAC is not currently in wide use, the study authors argue that expanding its use could help guide treatment for these millions of patients.

"The present study provides additional support for the use of CAC as a tool for refining cardiovascular risk prediction in individuals classified as intermediate risk by the [Framingham risk score]," the study authors write.

Specifically, the coronary artery calcium score would have accurately "reclassified" 25 percent of individuals from intermediate to high risk, and another 40 percent to low risk. This means more than half of the people previously labeled ambiguously as having intermediate risk would now be considered to be at either high or low risk, which would ideally lead to more appropriate care.

The implications of such an adjustment would be considerable. Heart disease remains the leading cause of deaths worldwide. Blockage of the arteries of the heart, or coronary heart disease, leads to heart attacks -- a condition that accounted for 1 out of 6 American deaths in 2008, according to the American Heart Association.

"While no one wants to be a statistic, the stark reality is that coronary disease is a leading killer," said Dr. Subha V. Raman, associate division director of cardiovascular medicine for quality at The Ohio State University. "Over half a million Americans find out each year that they have [coronary heart disease] while in the throes of a sudden cardiac death event,"

On the other side of the coin are the out-of-pocket expenses and the increased radiation exposure that this test entails. Previous studies show that radiation from CT scans has been linked to cancers.

Some doctors say the downsides of this test outweigh these benefits.

"I strongly disagree with the authors' conclusions," said Dr. Steven Nissen, chairman of cardiology at the Cleveland Clinic Foundation. "CAC scoring is a poor bargain with high costs and real harms."

Doctors Debate Benefits, Risks of Additional Heart Test

"The test is potentially worth the cost and small radiation risk only if it is going to change a clinical decision regarding the use of aspirin, blood pressure medications or cholesterol treatment," said Raymond Gibbons, professor of medicine at the Mayo Clinic. So for an intermediate risk patient who has additional risk factors, such as a strong family history of heart disease, he argues that this added test would be pointless, as these patients would be treated aggressively anyway.

Still, some doctors agreed with the idea that CAC could be used more widely to evaluate patients.

"With these new data, we have a much better understanding of the best utility for this tool and can understand much better how to apply this technology," Clyde W. Yancy, chief of cardiology at Northwestern University, wrote in an email.

"That coronary artery calcium scoring prevails against these and other candidate risk markers is the news of the day."