When someone close to us, or a beloved public figure, dies suddenly in their 50s (or even younger) from a heart attack, it suddenly raises our awareness of the deadly danger posed by undiagnosed heart disease. And indeed, statistics show that 50 percent of men and 64 percent of women who die suddenly from coronary artery disease (CAD) had normal cholesterol readings and no prior symptoms. But how do you know if you're at risk, and how bad that risk really is? Here are five new heart tests that show impressive results in detecting heart disease early and predicting future risk of heart attack and stroke.
Coronary Artery Calcium Scan (CAC)
Calcium is one of the main components in the plaque that builds up inside coronary arteries, narrowing and stiffening them and obstructing blood flow to and through the heart. A CAC score of zero is considered ideal; a score over 400 indicates severe atherosclerosis. Although CAC scanning is still one of the lesser-known heart tests, a study in the New England Journal of Medicine a few years ago determined that the CAC test was a "strong predictor" of heart attack and fatal heart disease. The researchers followed close to 7,000 people, testing them for CAC, then followed them for more than three years, correlating the data with the number of fatal or life-threatening coronary events. Those whose scores ranged from 100 to 300 were seven times more likely to die of a heart attack or other heart ailment than those with low CAC scores, and those with scores over 300 were even more at risk.
How it's done: Scans for coronary artery calcium are done via computed tomography, otherwise known as a CT or CAT scan. Unfortunately, CAC scanning, like any other CT scan, isn't without risk. Research by the National Cancer Institute and Columbia University found that the average range of radiation exposure from having such a screening test every five years would cause 42 additional cases of cancer among 100,000 men and 62 additional cases among 100,000 women. Some doctors therefore advise holding off on CAC scanning until other tests show elevated risk.
Who should get it: The American Heart Association (AHA) now recommends a CAC test for people over age 40 with risk factors for heart disease. Recent research also shows CAC tests are particularly useful as an incentive for treatment. Two Canadian studies published in 2012 found that having a higher-than-recommended CAC score doubled peoples' likelihood of sticking to a statin regimen and motivated 40 percent of those studied to lose weight.
How it's different: CAC scores are considered the strongest predictor of future coronary events in people who are otherwise asymptomatic, according to the American Heart Association (AHA). A study published in the August 2011 issue of The Lancet found that the CAC was a better predictor of heart disease than any other measure and can be used effectively to decide who should take statins and who's less likely to benefit.
Cost: $300 to $500; sometimes covered by insurance if ordered by a doctor as indicated by heart disease symptoms or "medium risk" of heart disease based on an assessment of risk factors. Check with your doctor and insurer first.
Corus CAD Explained
A genetic test, as opposed to a physical measurement, Corus CAD looks for evidence of narrowing or blockage in the coronary arteries at the molecular level. Blood samples are screened for the activity of 23 genes that exhibit changes when there's an obstruction in the arteries. It's gender specific, taking into account differences in how men and women respond to obstructive coronary artery disease.
How it's done: A blood sample is sent to the specialized laboratory of CardioDX, the company that makes Corus CAD. Results are available within 72 hours.
Who should get it: People experiencing chest pain, tightness, or pressure that could suggest a narrowing coronary artery. (One telltale sign that chest pain might indicate arterial blockage is if symptoms increase with exercise or exertion.) Shortness of breath or unexplained fatigue are other signs. You aren't a candidate for Corus CAD if you've had a previous heart attack or artery-opening procedure. Corus CAD also isn't recommended if you're diabetic, on steroids, having chemo, or taking immunosuppressive drugs.
How it's different: Corus CAD can detect multivessel coronary artery disease in people who are having unexplained chest pain but would otherwise be considered at low risk. Corus CAD is considered an alternative to myocardial perfusion image testing (MPI), which uses a radioactive agent to test for blockages in cardiac blood flow, followed by angiogram. For example, the New England Journal of Medicine recently reported that of 400 patients who underwent invasive angiography, 62 percent turned out to have no obstructive blockage. Corus CAD potentially could be used to more effectively sort out candidates prior to performing invasive angiograms.
Cost: Approximately $1,200. Some insurers cover Corus CAD, but most don't. Check with your insurance company first. CardioDX offers a financial assistance program to help those who can't afford the test.
High-Sensitivity C-Reactive Protein Assay Explained
Levels of C-reactive protein in the blood rise when there's widespread inflammation somewhere in the body. This can be due to bacterial or viral infection, but inflammation can also occur when plaque buildup irritates and inflames artery walls. Research shows that elevated levels of CRP correlate with increased risk of heart attack and fatal heart disease, possibly because inflammation damages and fragments arterial plaque, causing tiny portions of plaque to break off and be released into the bloodstream, leading to heart attack or stroke.
If your CRP level is in the upper third of that of the general population, you have double the risk of a heart attack compared with people whose C-reactive protein is within or below normal range. Some experts have also suggested that chronic inflammation may be one of the reasons heart disease is linked with gum disease.
How it's done: The hs-CRP test screens a blood sample for the level of the C-reactive protein. Fasting isn't necessary before hs-CRP testing. People with CRP values between 2.0 and 3.0 are considered at the high end of normal; a CRP score above 3.0 is considered high risk.
Who should get it: Anyone with elevated triglycerides and/or cholesterol who wants an additional measure of the likelihood of heart disease should consider this test. High blood pressure, diabetes, a family history of heart disease, or a history of smoking would also suggest that hs-CRP is a good idea. Currently the AHA recommends hs-CRP for those at "intermediate risk," but many clinics, including the Cleveland Clinic, order it for those with one or two risk factors. Women may be particularly good candidates for CRP testing; the Harvard Women's Health Study found hs-CRP a more accurate predictor than tests of cholesterol levels.
How it's different: Although a general blood panel determines the presence of fats and cholesterol in the blood, it doesn't indicate whether those increases are causing inflammation of the arteries. The standard CRP test measures a wider range of CRP levels; high-sensitivity CRP detects lower levels of the protein, making it a much more effective test for cardiovascular disease in people who are otherwise healthy.
Cost: $70 to $150 -- and hs-CRP is usually covered by insurance if you're referred by your doctor or cardiologist.
Carotid Artery IMT Ultrasound (C-IMT) Explained
One of the newest heart health tests to reach doctor's offices is a specialized, high-resolution ultrasound of the carotid artery called C-IMT. C-IMT uses sophisticated computer software to calculate the thickness of the intima and media, two layers of the lining of the carotid artery. Studies have found a strong correlation between the health of carotid arteries in the neck and the coronary arteries in the heart.
How it's done: C-IMT is performed in a doctor's office using specialized B-mode (brightness mode) ultrasound technology attached to a computer. It's considered safe and noninvasive and doesn't involve radiation.
Who should get it: Those with several risk factors for heart disease, cerebrovascular disease, and [stroke]. In November 2010, the American College of Cardiology Foundation/American Heart Association Task Force recommended the test for "asymptomatic adults at intermediate risk." Some heart experts think C-IMT -- along with CAC -- should gain more widespread use as a heart disease screening tool for the general population.
How it's different: C-IMT detects soft plaque as well as calcified plaque, otherwise known as coronary calcium. Studies show that while CAC is a better predictor of heart disease, C-IMT may be a better predictor of stroke, perhaps because a stroke can occur when bits of soft plaque lodge in cerebral blood vessels.
Cost: $150 to $300 or more. C-IMT is not usually covered by Medicare or other insurance, although Texas and Florida recently passed laws mandating that health insurers cover these tests when recommended by a doctor. The test is available at many walk-in heart clinics, which may offer discounted pricing.
Hemoglobin A1c Test Explained
The newest and least-known of the heart tests listed here is actually an extremely common test for diabetes, but it's only recently been used to detect heart disease. Also called glycated hemoglobin or glycosylated hemoglobin, the hemoglobin A1c test (HbA1c) is considered a measure of average blood sugar levels over time. More specifically, it measures the percentage of hemoglobin -- a protein in red blood cells that carries oxygen -- that's coated with sugar (glycated). The higher the A1c level, the poorer your blood sugar control.
How it's done: The hemoglobin A1c test is a laboratory blood test, but since it's not part of the standard lipid panel, your doctor has to order it separately. A reading between 5.0 and 5.5 is considered normal; above 5.5 to 6 percent indicates insulin resistance; 6.4 or over indicates diabetes.
Who should get it: According to the newest American Heart Association guidelines, hemoglobin A1c screening should be considered for people who've already had a coronary event or evidence of coronary disease. And since it's a relatively simple test, some doctors now are ordering A1c along with other standard tests to evaluate overall risk of cardiovascular disease in people with several risk factors but no symptoms. Historically, diabetics are at higher risk for cardiovascular disease, so anyone with diabetes should regularly be tested for hemoglobin A1c. Be aware, however, that if you're anemic, the A1c hemoglobin reading likely won't be accurate because of low red blood cell count.
How it's different: Unlike traditional glucose testing, which takes a reading at one point in time, hemoglobin A1c measures blood sugar levels over a period of months. The next time you have an annual screening with a standard blood panel and diabetes test, ask the doctor if HbA1c is included and if not, ask that it be added.
Cost: $60 to $100. It's usually covered by insurance for diabetes but only in rare cases for heart disease, and only for people who've already had a heart attack or other coronary event. But many experts predict this will change soon.