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New way to detect heart disease: noninvasive technology allows cardiologists to view a 3-D image of the heart.

New imaging scans are allowing physicians a noninvasive, closer, and detailed look at the heart, described as similar to holding a living heart in the hand. Until now, the most accurate procedure used to measure the degree of plaque buildup was the coronary angiogram, which remains the gold standard. But the method is time-consuming and invasive, requiring doctors to thread a tube from the groin or arm into the openings of the coronary arteries where a contrast agent is injected to visualize the inside of the vessels. The procedure is costly (about $4,000 or more for a diagnostic angiogram) and uncomfortable for the patient, who typically must stay in the hospital under observation overnight.

Using a new multidetector CT scan, doctors are capable of seeing not only the outline of the heart, but every detail inside and out. The test, which can be performed on an outpatient basis, can help detect subtle signs of heart disease, which can lead to early intervention and potential reversal. Unlike a conventional angiogram, the entire process takes about 15 minutes at a cost of roughly $400.

Researchers believe that the technology offers a novel way to diagnose heart disease, perhaps at an earlier stage and at less cost to the consumer and healthcare system.

To learn more about the revolutionary diagnostic tool, the Post spoke with Dr. Mario J. Garcia, director of the echocardiography lab and staff cardiologist at the Cleveland Clinic.

Post: Could you tell Post readers about the new heart scanning technology?.

Dr. Garcia: CT has been available for years. With more detectors now, the CT machine can take pictures in 3-D of the heart with very, very fine resolution and detail. Some of the images can help determine the anatomy of the coronary arteries. The technique requires that the patient receive contrast injected in a vein in the arm, and the scan takes about 15-30 seconds. The whole procedure takes maybe about 15 minutes. Available within a few minutes, the images can be shown to the patient. The information obtained from the scan, in many cases, is comparable with what could only be obtained in the past with cardiac catheterization or coronary angiogram, which is an invasive procedure.

Post: What are the advantages of CT imaging, as opposed to an angiogram?

Dr. Garcia: The coronary angiogram is the gold standard. It remains the final word. It offers more fine detail of the smaller branches of the coronaries, and if you find a blockage while doing an angiogram, you could fix it at the same time during the procedure. That is the advantage of the coronary angiogram. Its disadvantage is that it is invasive and takes more time. There is also a small risk of damaging the arteries where one does the stick to place the catheters through, as well as a small risk of such complications as stroke or heart attack.

On the other hand, the CT angiogram can provide images of the coronary arteries that, in most patients, are quite comparable to the coronary angiogram, particularly in those who are not too overweight and who have stable heart rhythms. In addition, the CT scans can image the wall of the arteries, while the coronary angiogram only shows their lumen. The CT can show if there are accumulations of calcified or noncalcified atherosclerotic plaques, which is quite important because even though someone may have relatively minor blockages, the disease in the vessel wall may need to be treated with such drugs as statins.

Post: Would a CT scan of the heart aid in the early detection of heart disease, as opposed to evaluating a person, say, who already has heart disease?

Dr. Garcia: Knowledge is still being examined, and the idea is trying to find acceptance among cardiologists in the community. In many cases, such procedures as regular stress tests yield inconclusive results, and up to 20 percent of the time, these are wrong--either falsely positive or falsely negative. In those cases until now, you could either hope you were right or send the patient for an invasive angiogram. In those situations, I believe the CT scan could be useful.

Post: Some have referred to the new heart scan procedure as the "mammogram of the heart," in that it aids in early detection of disease.

Dr. Garcia: In the future, that could be possible. More studies are needed to evaluate and validate that suggestion. The risk of that analogy is that you are implying everyone should have a CT scan of the heart once every year. Certainly, very few physicians and centers have the expertise or the equipment necessary to do a high-quality study, whereas the mammogram is available almost everywhere at this point. Second, the radiation that you receive undergoing a mammogram is much less, so I wouldn't really like to do this on a yearly basis with everyone, but rather on selective people at risk and much less often.

Post: Who would be a good candidate for a scan?

Dr. Garcia: Obviously, candidates for the scan would include patients with risk factors for coronary artery disease--such as a family history, elevated cholesterol, hypertension--that put them at risk for developing atherosclerosis, particularly patients who have chest pain symptoms. Certainly, this is still evolving, and there are going to be many patients that, unfortunately, will not benefit in the immediate future because they may be too obese. Image quality in obese patients is not very good. Also, a patient with irregular heart rhythm, such as atrial fibrillation, may experience problems getting good pictures. Engineers in this technology are trying to solve those problems, but right now this technique is limited to patients not excessively overweight but with regular heart rhythms.

At this point, the CT scan of the heart will not eliminate the necessity of doing a stress test. A very good test, the stress test provides a lot of information, but if a patient like this would have a stress test that is borderline or negative, then the information of the CT would be very powerful and complementary.

Post: Would the scan be useful in patients who present to the emergency room with chest pain?

Dr. Garcia: Chest pain could be a heart attack or myocardial infarction. If the information at the emergency room or after stress tests is inconclusive, patients who are still suspected of having coronary artery blockages would benefit from the CT heart scan.

Post: Are other tests done in conjunction with the scan?

Dr. Garcia: I suspect that in the near future this test will be offered in the emergency room. In outpatient and ambulatory patients, we still will continue to use the judgment of the emergency room doctor, the cardiologist, or the internist who determines the individual patient risk based on symptoms, family history and other risk factors, as well as the results of blood tests, electrocardiograms and stress tests. But again, in situations where these results are inconclusive, the scan might be able to provide a final arbitration.

Post: Is any risk associated with the multidetector CT scan?

Dr. Garcia: The only risk, other than the radiation expo sure, is the possibility of side effects from the contrast, which is an iodinated dye. A small percentage of the population is allergic to iodine, and they can develop an allergic reaction. Also, people with kidney failure are potentially at risk for getting worse from intravenous contrast.

Post: How many centers around the country are doing this scanning technique right now?

Dr. Garcia: Centers offering the CT angiogram, utilizing an injection of contrast--the equivalent of the coronary angiogram--are very few, probably less than 20-25 in the country. The best way of finding out where they are located is through the three major vendors of equipment--Siemens, General Electric, and Philips.

Post: From your point of view, what is the benefit?

Dr. Garcia: I think the technology is very promising. It will be able to identify patients at risk much better than any test that we have available. It may be able to diminish the number of misdiagnoses that occur. For example, some patients who come to the emergency room with chest pain get discharged, then end up having a heart attack after discharge. Those cases will be less likely to occur once this technology becomes widely adopted.

In many patients with chest pain, the electrocardiogram and blood tests show clear evidence of a heart attack. But others don't manifest electrocardiographic or blood test changes, and they are often erroneously diagnosed as having stomach, muscular or bone aches and may get discharged from the hospital. The majority of these patients do not have a heart attack, but a few do. Medicine is not a perfect science.

Post: Do you think the scan could potentially save the healthcare system money by reducing healthcare costs?

Dr. Garcia: You can make the argument that ff used in the right hands and with caution and appropriate indications in the right type of patients, you could save lives and money. On the other hand, if adopted by physicians just as a commercial enterprise, it could potentially increase costs. One fact most experts agree on is that this test has the potential to change significantly the way that we will be practicing medicine.

Post: From the patient's perspective, what preparations are needed?

Dr. Garcia: The beauty of this procedure is that you may see a patient on a Friday afternoon in a clinic setting and have some suspicion, but not complete evidence, that the patient may have a blocked artery. If so, you could send them to a CT scan suite, get them ready, do the study, and receive an answer right away. If you schedule a cardiac catheterization, the patient may have to wait, in many cases, until the following week to know what he or she is dealing with. Cardiac catheterization takes time, and most centers don't offer these services on weekends, unless in an emergency situation. The new scan can be done very quickly and gives you pictures immediately. We are able to show the arteries to patients while they are still lying on the table within a few minutes. Patients get incredible satisfaction. They are also more convinced when we tell them that they may need to take drugs for life to reduce the risk of having a heart attack.

Post: If you do discover a blockage, what would be the next step?

Dr. Garcia: The next procedure you would do is a cardiac catheterization with the intent of fixing it. In addition to helping patients individually, the use of CT could help hospitals to more efficiently use their cardiac catheterization suites, so instead of having to do maybe half of the cases for only diagnostic screening, they could become more selective and mostly schedule patients who will require an intervention. In other words, the diagnosis could be done ahead of time with a CT. If an intervention is necessary, the patient would be taken to the cath lab. That process is more efficient and will expedite care. It actually could save dollars to the health system in that way.

Post: How soon do you think that this will be more widely available?

Dr. Garcia: From what I have seen in the evolution of the technology, as well as patient, physician and media interest, I think within the next one or two years this will be widely available. Some centers in the United States have already acquired the expertise to perform the CT scan of the heart, but the procedure is still not widely available. Obviously there is a learning curve to interpret these studies, and I would recommend patients consult with their physicians to find out where they should go.
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Title Annotation:Healthy Heart Report
Author:Perry, Patrick
Publication:Saturday Evening Post
Article Type:Interview
Geographic Code:1USA
Date:Mar 1, 2005
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