What else is there?

This question comes up frequently:

Aren't there any alternatives to heart scans performed on a CT or EBT device?

Yes, there are.

First of all, heart scans are performed best on an electron-beam CT device (EBT) or a 64-slice multi-detector CT (MDCT) device. (While they are also obtainable through less-than-64 slice CT devices (e.g., 16 slices and less), I would advise against it because of the excessive radiation exposure and poor accuracy.) CT heart scans are not to be confused with now more popular CT coronary angiograms, which are performed on the same devices but require intravenous x-ray dye and many times more radiation.(See CT scans and radiation exposure and Heart scan frustration.) Heart scans currently form the basis for the Track Your Plaque program, a program of tracking plaque in the hopes of stopping or reversing the otherwise inevitable 30% per year increase.

Let's confine our discussion to people without symptoms, meaning people like you and me sitting at home, not in an emergency room having chest pain or other similar acute symptomatic presentation.

Among the other ways to uncover hidden coronary plaque:

--Heart catheterization--to yield a coronary angiogram. Yes, this does tell us whether coronary plaque is present. However, it is invasive, expensive, and crude. (I've performed 5000 over my career; they are crude, though useful, tools in acute settings like unstable symptoms or heart attack, a different situation.) Coronary angiography is also non-quantitative. While they provide a value like "40% blockage mid-way in right coronary" or "90% blockage in left anterior descending" they do not provide a trackable lengthwise index of total plaque volume. Identifying severe blockages in people with symptoms leads to stents, bypass surgery and the like, but it is not practical nor of long-term usefulness in apparently, healthy people without symptoms.

--Carotid ultrasound--Here's is where a lot of confusion comes from. Standard carotid ultrasound (U/S) performed in virtually every hospital and many clinics will yield crude qualitative results, e.g., "16-49% stenosis (blockage) in right internal carotid artery". The crude value range is because much of carotid U/S is based on flow velocities, not just direct visualization of the plaque itself ("2-D imaging). However, if carotid stenosis of any degree is identified, the likelihood of silent coronary plaque is much greater.

Limitations: The qualitative, non-quantitative nature of carotid U/S make it difficult to follow long-term in a precise way. Also, this is carotid plaque, not coronary plaque. It makes it very difficult to follow carotid plaque as an indirect means of tracking coronary plaque. The two arterial territories, carotid and coronary, do not track together: there are divergences in many people, with carotid plaque absent in some people with advanced coronary plaque, carotid plaque more susceptible to different risk factors than coronary. So carotid U/S is helpful for its own purposes, but not terribly helpful for coronary tracking.

How about carotid intimal-medial thickness (CIMT) obtained also with carotid U/S? CIMT is a useful index of bodywide atherosclerosis. CIMT is simply a measure not of plaque (and is measured in regions of the carotid artery away from plaque), but of the thickness of the lining of the carotid arteries. Everybody has a measurable CIMT, but it thickens as atherosclerosis grows. CIMT is a radiation-free test that takes several minutes.

Limitations: Hardly anybody does it outside of research protocols. I know of no hospital or clinic in my area that performs CIMT, though it is slowly being adopted in some centers. It is also difficult to rely on repeated tests, because there is substantial variation when one technologist or another performs it. CIMT is also a flawed index of coronary plaque. When CIMT is compared to heart scan scores, CT coronary angiography, or conventional coronary angiography, CIMT correlates about 60-70% with the degree of coronary atherosclerosis.

CIMT is therefore a useful test for research, but a distant 2nd choice--if you can obtain it.

--Ankle-brachial index (ABI)--ABI is a crude measure, simply a comparison of the blood pressure (obtained with a blood pressure cuff) in the legs divided by blood pressure in the arms. The ratio is called ABI. Any ABI <1.0, meaning less pressure in the legs compared to the arms, is indirectly indicative of advanced coronary disease. ABI is, in fact, a very powerful predictor of cardiovascular events. If ABI is <1.0, your future risk for heart attack is very high, even in the absence of symptoms.

Limitations: The vast majority of people with heart disease, even those having undergone stents or bypass surgery, have normal ABI's. Virtually all people with high heart scan scores have normal ABI's. In other words, ABI is a measure of very advanced atherosclerosis only.

--Stress tests--I lump all stress tests together in their various forms, e.g., stress thallium, stress Cardiolite, stress Myoview, persantine/adenosine Cardiolite, dobutamine echocardiography, etc. Stress tests are tests of coronary blood flow, not of plaque. Stress tests are useful in people with symptoms, like chest pain or breathlessness, since stress tests are provocative tests that can help determine whether reduced coronary blood flow is the cause behind a symptom, or whether hiatal hernia, esophagitis, gallstones, pleurisy, musculoskeletal causes, or some other process is behind symptoms.

Limitations: Stress test are virtually useless in people without symptoms. This is why people like Tim Russert and Bill Clinton, both without symptoms, underwent several (Russert 3, Clinton 5) nuclear stress tests---all normal. You know what happened to them. Stress tests do not reliably uncover hidden coronary plaque in people without symptoms. Stress tests are, like coronary angiograms, non-quantitative. They are normal or abnormal.

Outside of experimental settings, that's it.

You can probably see why I advocate CT heart scans for tracking plaque. I do not advocate heart scans because I sell them (I don't), because scan centers pay me to say these things (they don't, and in fact my relationship with my usual heart scan centers has become deeply contentious, though I still endorse the technology). I say that heart scans are superior because they are, in 2008, the only way to 1) identify and 2) track coronary plaque that is easy, safe, low-radiation, and reasonably priced (<$200 in Milwaukee at 5 centers).

The need for a technology that allows tracking of plaque, not just initial identification, is also an important distinction. People who've had some measure of atherosclerosis all catch on to this eventually. "Can I reverse it?" is an inevitable question once the disease is identified in some way. So a tool for tracking over time to gauge the success or failure of a program of prevention can be assessed.

Perhaps in 10 years, another technology will emerge as the preferred means to do the same, but better. If that proves true, we will convert to that technology. But today heart scans performed on CT heart scans are the only rational way to both detect, then track, coronary atherosclerotic plaque.

Comments (11) -

  • Steve

    9/7/2008 3:29:00 PM |

    is it true that heart scans do not show soft plaque,which minimizes their benefit since soft plaque is the real concern

  • lizzi

    9/7/2008 4:27:00 PM |

    I think that CIMT may be more widely available in different areas of the country.  I practice in Los Angeles and have the luxury of having Dr. Budhoff 15 minutes away.  I like that my referrals for EBT will contribute to a research protochol.  In addition, many internists are purchasing an ultrasound machine, hiring a tech, and providing CIMT for $350.00. There are two approved CIMT protocols, one which requires only a single measure of IMT, the other which requires six measurements.  Guess which one is more accurate? I am also fortunate that the internist next door to me hires an excellent tech and does 6 measurements.

  • lizzi

    9/7/2008 4:46:00 PM |

    Dr. Davis.  Have you seen P Bhaggi's article in Lancet 8/28/08?  His hypothesis is that even "safe" doses of radiation MAY increase CV disease risk. (<5Gy). He sites a linear association between radiation exposure for peptic ulcer disease (1.6 - 3.9 Gy) and CV disease risk.  I don't know how Gy equates to Msv.

  • Bella6

    9/7/2008 6:58:00 PM |


  • Anonymous

    9/7/2008 8:49:00 PM |

    Any newer technologies that look promising ?

  • MedPathGroup

    9/8/2008 1:28:00 AM |

    Very relevant information about CT Heart Scan and other alternatives to tracking coronary plaque. I will definitely add this to my research. I will keep on visiting your blog site. I've been a reading a lot of your posts and they are really interesting. Keep it up.

  • Anonymous

    9/8/2008 4:53:00 PM |

    in the new york area they do CIMT and use it as a proxy for CAD.  I would say that 60-70% correlation is pretty good and need for heart scan not necessary if CIMT is abnormal.

  • JD

    9/9/2008 1:56:00 PM |

    For Dr. Davis. He probably is aware of this type of study but thought I would post it.


    "For the study, researchers used cardiac and CT scans to measure multiple fat depots in 398 white and black participants from Forsyth County, N.C., ages 47-86. They found that the amount of fat a person had deposited around organs and in between muscles (nonsubcutaneous fat) had a direct correlation to the amount of hard, calcified plaque they had."

  • mike V

    9/9/2008 6:07:00 PM |

    See Heart Scan Blog
    Sunday, December 03, 2006
    Calcium reflects total plaque

  • Maureen Zilly

    9/9/2008 6:19:00 PM |

    I think that the Los Angeles Times story “CT scans can be better medicine for doctors than for patients” portrays an inaccurate picture of how physicians use computed tomography to care for their patients.  

    To begin with, the piece overstates the growth and utilization of CT. For example, the story uses GAO statistics to demonstrate an increase in CT scans, but the GAO's recent report on medical imaging did not account for the most recent data available. Had the GAO used the more current 2007 Medicare claims instead, its report would have actually shown a decrease in the growth of medical imaging services in recent years.

    Next, the story presents biased information as fact. Insurance companies are wholly motivated to pay less for health care services, which includes limiting medical imaging scans. In fact, insurers have created a cottage industry, called Radiology Benefit Managers, with the sole purpose of refusing coverage for scans. By citing subjective and unverified insurance company-generated analysis of how many scans are "inappropriate," readers are presented with a skewed view about how and why physicians order scans.  

    Clearly, CT has grown as it's become integral to modern day medicine. From best practices to patient advocate guidelines, CT is a powerful tool for improving patient outcomes. But, the larger issue is ensuring patients have access to the right scan at the right time. In computed tomography this is even more important because of the radiation CT employs to generate what are often life-saving images.    

    That's why it is vital for payers -- both private and Medicare -- to ensure that healthcare decision making remains between the physician and patient. The recent Medicare bill is an important step in the right direction because it embraces both accreditation and appropriateness criteria, and it is approaches such as these that will ensure that each scan ordered is appropriate, effective and safe for patients.

    Lastly, the article also claims that CT angiograms (CTA) are "less accurate" than traditional angiograms, but research has indicated otherwise. A recent study published in the Journal of the American College of Cardiology, for instance, found that CTA was 99 percent as effective in ruling out heart disease as the more expensive and invasive coronary angiography traditionally used by physicians. This CTA study is just one of many peer-reviewed data points demonstrating how medical imaging, and CT specifically, improves health outcomes and reduces overall costs.

    Maureen Zilly
    Medical Imaging & Technology Alliance

  • Anonymous

    9/10/2008 4:43:00 PM |

    Are there any options for young adults with a strong family Hx?  I contacted TYP, but they told me that based on my age, the risk of radiation exposure outweighs the potential benefits of the scans.  I'm a 26 y/o female.