Be Wary of CardioVision Assessment

Stephen Barrett, M.D.

To measure blood pressure, a cuff is placed around the patient's arm and inflated until the pressure inside the cuff prevents blood from flowing into the brachial artery at the elbow. Then the cuff pressure is gradually lowered and is measured when blood flow resumes (systolic pressure) and when it is fully restored (diastolic pressure). As people age, their arteries tend to get less flexible. The CardioVision MS-2000 is an electronic blood pressure device that calculates an "arterial stiffness index" ("ASI") related to how fast the blood pressure falls as the air pressure is released from the blood pressure cuff. The device, which sells for $5,995 [1], is primarily marketed in the United States by International Medical Device Partners (IMDP), Inc., of Las Vegas, Nevada. According to an IDMP brochure:

Until the invention of CardioVision®, there was no easy, inexpensive or quick way to determine if a person's vessels had lost flexibility. Many people are never aware that they are walking around with this "silent killer" until they experience their first heart attack from occluded vessels. It has been estimated that 60-70 million Americans harbor this silent killer and should make both life-style changes, such as getting more exercise, changing their diet, quitting smoking, and reducing their cholesterol. While everyone needs to adopt these changes, sometimes life-style changes alone are not enough. CardioVision® identifies people who don't even think they have a cardiovascular problem because they are non-smokers and exercise regularly and watch their diet. Consequently, the ASI can be viewed as another cardiovascular "risk factor," just like high blood pressure or a cholesterol level above 200. Additionally, we think that the ASI can be used to follow cholesterol lowering therapy and other "risk factor" changes [2].

The above paragraph suggests that using the ASI to identify people at risk will save lives. However, the only modifiable risk factor that the ASI can detect is high blood pressure. If someone's pressure is high, standard blood pressure testing will reveal that. The paragraph also suggests that periodic use of the test is useful to measure the patient's progress. However, ordinary blood pressure readings, which can be done by the patient at home, are just as effective and are far more cost-effective.

Several studies have examined the impact of various factors on arterial elasticity and whether arterial stiffness is an independent risk factor for cardiovascular disease. So far, no clinical studies have demonstrated that the CardoVision or any similar device can usefully guide patient management and improve clinical outcomes. Even worse, a study of adults who had five consecutive measurements taken five minutes apart on a single day and repeated about five months later demonstrated that CardioVision measurements varied too much to be trustworthy [3].

For these reasons, leading medical professional organizations do not recommend arterial flexibility tests for cardiovascular disease assessment and insurance companies regard them as experimental and don't knowingly pay for their use [4].

FDA Status

The CardioVision MS-2000 has 510(k) clearance for marketing as an automated blood pressure device for the following intended use:

The MS-2000 is used by health care professionals to measure blood pressure data (systolic, diastolic and mean pressure) and heart pulse rate. The MS-2000 also generates pulse wave patterns which can be used as an initial screening device to determine if patients have potential underlying cardiovascular disease that might require more specific diagnostic evaluations by physicians or other health care providers [5].

Although many Web sites claims that the MS-2000 is FDA-approved, it is not. To gain approval, a manufacturer must demonstrate safety and effectiveness through “adequate and well-controlled” clinical trials [6]. Clearance merely indicates that a device is considered safe based on substantial similarity to a previously cleared or approved device. Put another way, the FDA merely said the MS-2000 could be marketed as a blood-pressure device but did not approve it for determining cardiovascular risk or monitoring cardiopreventive programs.

Actual Use

If the MS-2000 has no practical use, why would practitioners use it? One reason is to help sell chelation therapy, which several users claim can reduce arterial stiffness. The Web site of Vancouver naturopath Tom Glew, for example, states:

Our clinic has a CardioVision instrument which measures hardening of the arteries also referred to as arterial stiffness index. This tool gives a clear indication of the need for chelation therapy and can be used to monitor your progress and response to the treatment. Blood tests, although necessary to measure cholesterol and other risk factors, do not measure arteriosclerosis or hardening of the arteries directly whereas the CardioVision does [7].

Chelation therapy has no proven value against cardiovascular disease and should be regarded as a fraud [8,9]. In 2000, the Clinical Journal of Alternative Medicine (a now-defunct journal published by the main chelation advocacy group) published a study that compared CardioVision measurements of 18 patients before and after EDTA chelation therapy [10]. The study was poorly designed because there was no control group and the investigators who did the measurements were not blinded. The authors concluded that chelation had increased the arterial flexibility and that CardioVision testing might help demonstrate that chelation could prevent cardiovascular events such as heart attacks. However, the data within the study showed just the opposite. Although 12 of the patients who began with high ASI numbers had lower readings after chelation, 5 who began with low ASI numbers wound up with higher ones. Thus, if chelation actually affected arterial stiffness and the CardioVision test was accurate, chelation may have made some patients worse. Moreover, in some patients repeat readings on the same day varied by more than 10%, which is a sign that the test is not reliable.

A second reason for using CardioVision may be financial. A CardioVision brochure suggests that $100 per test is an appropriate charge and that about a dozen insurance companies have paid from $31.56 to $100 for the test [6]. The same document contains a 1998 letter from IMDP medical advisor Donald E. Rediker, M.D. of Mission Vallejo, California, which states:

To date, I have used CardioVision as a routine non-invasive screening device on over 200 patients in a busy 40 physician clinic. The results as to sensitivity and specificity are very encouraging as a routine screening device, and we have therefore incorporated CardioVision in all workups for routine screening and evaluation of CHD patients. Clinical data suggest that it compares very favorably to standard treadmill testing. We are currently completing the write-up of our studies which will be submitted for presentation to leading cardiology scientific sessions and journals recommending the routine use of this screening device. With over 45 million Americans, many unknowingly, suffering from hypertension, CardioVision is highly recommended as a screening device to aid the physician in identifying and managing these people. From personal communications, I know that this device is being used in a positive manner, and in the same screening capacity at other major medical centers across the United States, such as Harvard-Massachusetts General Hospital, Scripps Clinic and Hospitals, Sharp Grossmont in San Diego, and many others.

I recommend that you to evaluate this state-of-the-art screening device for routine use in your health and fitness club, rehabilitation center, athletic department, dental practice, or community screening organization [11].

I don't know whether Rediker is still using the test routinely, but the IMDP Web site still identifies him as a medical advisor. He may have presented data at a medical meeting, but my Medline search of journals found no relevant reports authored by him.

The IMDP brochure recommends using CPT code 99090 to bill for CardioVision screening. This code stands for "analysis of clinical data stored in computers (eg, ECGs, blood pressures, hematologic data)." I doubt that the insurance companies who pay such claims know what procedure they are covering.

The Bottom Line

Arterial stiffness measurements can identify some people who are at risk for cardiovascular disease. However, they are not as reliable or cost-effective as standard blood pressure and cholesterol screenings. Some practitioners use CardioVision as a gimmick to sell inappropriate chelation therapy. Some use it as a simple way to boost their income, and some may be submitting inappropriate procedure codes on insurance claims. My advice is to avoid practitioners who use it.

References

  1. Standard price list. Health Management System, Plano, Texas, Jan 1, 2009.
  2. Greenwood JR. Arterial stiffness index. Page 4 in CardioVision featuring the Arterial Stiffness Index (ASI): Selected letters., papers, and pertinent information. Downloaded from IMDP Web site, March 20, 2010.
  3. Sharma GK. Assessment of test repeatability of arterial stiffness index. Blood Pressure Monitor 10:271-274, 2005.
  4. Cardiovascular disease risk tests. Aetna Clinical Policy Bulletin 0381, Aug 7, 2009.
  5. FDA clearance: K961144. Tourito Engineering Co., Inc., March 12, 1997.
  6. Yellin AK. What are 510(k) clearance and premarket approval? Device Watch, Jan 9, 2009.
  7. Chelation therapy. Westside Naturopathic Clinic Web site, accessed March 21, 2010.
  8. Green S. Chelation therapy: Unproven claims and unsound theories. Quackwatch, July 24, 2007.
  9. Atwood KA and others. Why the trial to assess chelation therapy (TACT) should be abandoned. Medscape General Medicine 10(5):115, 2008.
  10. Chappell LT and others. Brachial artery stiffness as an outcomes measurement for EDTA-treated patients with vascular disease. Clinical Practice of Alternative Medicine 1:225-228, 2000.
  11. CardioVision featuring the Arterial Stiffness Index (ASI): Selected letters., papers, and pertinent information. Downloaded from IMDP Web site, March 20, 2010.

This article was revised on March 25, 2010.

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