Capital Cardiology Associates
Can Doctors Predict Heart Attacks?
A new procedure can pinpoint within years your risk of heart attack
Every year there are more than 3 million heart attacks in the United States. The American Heart Association breaks that down to about one heart attack every 40 seconds. Most Americans are aware that lifestyle habits, a healthy diet, and regular visits with their doctor to monitor their risk of heart disease help prevent us from becoming a statistic. Even with testing today that can gauge the risk of a heart attack or cardiac event within the next ten years, doctors are still searching for the “Holy Grail” of detection.
During a recent episode of HeartTalk presented by Capital Cardiology Associates, Dr. Robert Benton addressed the topic of predicting the risk heart attack thanks to new clinical testing being performed with CT scanning equipment. Dr. Benton is the Clinical Research Director of Capital Cardiology Associates and spoke about research on a new detection system, known as the Fat Attenuation Index (FAI), to measure plaque and detect risk.
The CT Scanner
The study involved a team of researchers from the University of Oxford in England and the Cleveland Clinic in Ohio who found a new application for CT Scans. Their detection system, known as the Fat Attenuation Index (FAI), uses standard non-invasive computed tomography (CT) scanning technology to measure plaque and detect risk. This helps “predict” and identify markers, noninvasively, to look at coronaries.
A traditional CT scan is an x-ray procedure that combines many x-ray images with the aid of a computer to generate cross-sectional views of the body. Cardiac CT uses the advanced CT technology with intravenous (IV) contrast (dye) to visualize your cardiac anatomy, coronary circulation and great vessels. Capital Cardiology Associates uses a state-of-the-art multi-row detector CT scanner. With multi-slice scanning, it is possible to acquire high-resolution three-dimensional images of the moving heart and great vessels. Learn more about cardiac CT scanning, here
“‘What’s the risk of something bad happening to me?'”, opened Dr. Benton. “Now that’s a complicated question because there are known risk factors go into the answer: family history, medications you are on, lifestyle, and many other factors. We have formulas that can give an estimate over 10 years what your risk might be. Now that’s over the next ten years, I didn’t say tomorrow morning or 9 years and 11 months from now. One of the toughest things a doctor has to do is predict how long a person has to live. We are notoriously terrible at predicting that.”
Doctors have long been searching for the identifying markers that can better pinpoint the immediate risk of heart attacks developing. Dr. Benton broke down the current diagnosis system. “When you go to your cardiologist, they can order biomarkers, a blood test for inflammation, for example. You can put these results into formulas that give a general idea on where you fit in with your peer group over the next ten years. How do we give people information that is more useful to them on if an event is going to occur this year, this month, or this week? We aren’t there yet.”
“But one thing we do know is that in heart attack patients, 50% of people have normal cholesterol levels. That tells us there are other things going on. You’ve heard doctors talk about plaque in your arteries. This plaque forms a blockage in the artery causing a lack of blood flow in the artery. Many of those people had a prior to a heart attack, insignificant blockage of 10%, not 80%. What is it about that 10% blockage that makes it crack when, let’s say, bowling or running; what makes that heart attack occur?”
3D rendering of plaque in arteries
Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. Over time, plaque hardens and narrows your arteries. This limits the flow of oxygen-rich blood to your organs and other parts of your body. “We think what causes the plaque to break is inflammation, meaning that the white blood cells have infiltrated the plaque, making it soft,” stated Dr. Benton. Your white blood cells begin to attack the plaque as part of your bodies natural defense. As the blood runs by the weakened plaque, your blood pressure rises, or the heart rate goes up, it causes the plaque to rupture. This triggers a heart attack or stroke as the plaque now clogs another artery in your heart, or in the case of stroke, the blood supply to part of your brain is interrupted or reduced, depriving brain tissue of oxygen and nutrients.
How Is FAI Different Than A Calcium Score?
Currently, to get a better assessment of your doctor would order a coronary CT calcium scan of your heart. A CT scan is a low risk procedure that has been around since the 1990’s. This 30-minute procedure looks for calcium deposits in the coronary arteries that can narrow arteries and increase the risk of heart attack. A calcium score of zero gives you a risk of somewhere in the range of .5% risk of heart attack over the next five years on an annual basis and there’s nothing else, no math model, no stress test, or anything else. The highest score we have seen a symptomatic person was in the 12,000 range, that’s very usual.
“Calcium score can identify plaque but doesn’t tell us how strong or weak it is,” added Dr. Benton. “This new study is looking at the small amount of fat that surrounds the coronary arteries, naturally, to cushion and protect arteries. What this study did is look at the quality of that fat. Specifically if the fat became liquid or soluble as a marker of inflammation. They came up with a technical scale and found that if you had this attenuation, that is a predictor of future of events within three to four year range.” Those with an abnormal FAI number were up to nine times more likely to have a fatal heart attack in the next five years.
Dr. Benton expanded on the findings of this new research. “What we understand about this process is that when the fat becomes unhealthy, that’s a marker of inflammation in the plaque itself. We are still researching the causes of the inflammation, but the two are related, and being able to measure this with a low-radiation CT scan, we can judge the stability of the plaque. These tests would give us the information we need to tell a smoker, for example, to stop smoking that cigarette because they are more immediate risk of heart attack due to the inflammation of plaque caused by tobacco. This testing is not ready for primetime right now but I would say within a year or two, it will be ready for a wider population of patients.”
Soon a CAT scan would be able to tell us the amount of calcium, the bulk of the plaque in your heart’s arteries and the nature of that plaque, in terms of inflammation. “There is so much information that is right over the horizon,” said Dr. Benton. “There will be more clinical trials on which patients should have this type of procedure. Your going to look for people that are in the moderate risk group. People who have risk factors like family history, chest pain at times, or other biomarkers in their blood. What’s interesting in this test is that, you are going to try and identify those people who have, the 10% blockage, who won’t have chest pain. They are the ones who would have an acute heart attack. Those are the type that occur suddenly. The 10% are also the ones at a higher risk of heart attack because we already can identify those at 70% or greater blockage.”
Written by: Michael Arce, Host of HeartTalk presented by Capital Cardiology Associates
Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.