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28 April, 2016

Benefits to CT Calcium Scores

Benefits to CT Calcium Scores

CT calcium score is a strong predictor of a patient’s risk for heart attack. However, this widely available and relatively inexpensive exam is often underutilized. New research provides additional evidence supporting the benefits of CT calcium scoring.

Warranty Periods for CT Calcium Scores

Research published August 2015 in JACC: Cardiovascular Imaging discusses the “warranty period” for a calcium score of 0. It has been shown that a calcium score of 0 offers a short-term (5-year) warranty period suggesting a low chance of a major adverse cardiovascular event (MACE). However, the long term prediction for MACE in patients with a calcium score of 0 has not been evaluated until the present article by Valentina et al.1.

In this study, they evaluated a total of 9,715 individuals undergoing coronary artery calcium(CAC) imaging that were stratified by age, Framingham risk score (FRS), and National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) categories. Patients were followed for a mean of 14.6 years (range 12.9 to 16.8 years). Cox regression, area under the receiver-operating characteristic curve, and net reclassification information were used to assess all-cause mortality, discrimination, and reclassification of a CAC score of 0 compared with the FRS and NCEP ATP III, respectively. A warranty period was pre-defined as less than 1% annual mortality.

The results of this study concluded that a CT calcium score of 0 confers a 15-year warranty period against mortality in individuals at low to intermediate risk that is unaffected by age or sex. Furthermore, in individuals considered at high risk by clinical risk scores, a CAC score of 0 confers better survival than in individuals at low to intermediate clinical risk with any CAC score.2

It has been shown that a positive CT calcium score increases the risk of future MACE with the greater the amount of calcification correlating with increasing risk. Even in clinically low risk groups, that may not be offered statin therapy, a positive CT calcium score can change the statin recommendation to the treatment arm.Recent studies of new cholesterol guidelines have generated intense discussion over broadening the scope of statin eligibility and potential over-treatment of low risk individuals likely to benefit from therapy.

CT Calcium Score & Patient Management

An article by Nasir et al, published October 2015, evaluates whether it is feasible to downstage the need for medical management in patients with a low to intermediate clinical risk but demonstrating a calcium score of 0. 3

Researchers discusses whether a calcium score of 0 can place the patient into an even lower risk category allowing for many of the patients that would fall into the statin treatment group to be reclassified into the non-statin treatment group. This study has the potential to prevent overtreatment as would be supported by using present statin guidelines and make treatment with statins less compelling and thus potentially reducing costs and side-effects from statin therapy.

According to Leslee Shaw, PhD, FSCCT, FACC, FASNC, FAHA, a co-author of this study, major findings of this study include:

  1. Nearly two-thirds of adults aged 45 to 75 years are either recommended or considered for statins by current guidelines.
  2. Almost one-half of these candidates have no coronary artery calcium, and their actual risk is much lower than the threshold suggested by the guidelines to consider statin therapy. The greatest reclassification was noted in those at intermediate level of estimated risk by traditional risk factors.
  3. The knowledge of significantly lower reclassified risk with absence of coronary artery calcium can be valuable in better informing patients of choices, who may consider avoiding statins to focus on prudent lifestyle changes.
  4. From a societal prospective, the estimated number of individuals to treat in order to prevent one cardiac event is very high. This finding should stimulate dialogue on best strategies for appropriate resource therapy, surgery, risk factor reduction, lifestyle modifications or any combination.

CAC imaging is a relatively inexpensive examination (our present charge $285.00), performed in less than 10 minutes and performed with very low radiation. It is, in my opinion, one of the most underutilized tests offered especially for the amount of information that can be obtained for asymptomatic patients needing cardiac risk assessment.

There are numerous articles demonstrating better drug compliance with statin therapy when the patient has been shown that they have calcified plaque and therefore coronary artery disease. I hope that this information provided to you will be useful and will assist you in the care and work-up of your patients. Please do not hesitate in contacting any of the radiologists at Rolling Oaks Radiology if you have any questions about this topic or any other radiology related issues.

Regards,

Roy Gottlieb, D.O., FSCCT

 

 

 

BIBLIOGRAPHY:

  1. Valentina Valenti, Bríain Hartaigh, Ran Heo, et.al.

A 15-Year Warranty Period for Asymptomatic Individuals Without Coronary Artery Calcium: A Prospective Follow-Up of 9,715 Individuals

JACC: Cardiovascular ImagingVolume 8, Issue 8August 2015Pages 900-909

 

  1. P. Greenland, L. LaBree, S.P. Azen, T.M. Doherty, R.C. Detrano

  • Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals. JAMA, 291 (2004), pp. 210–215

  1. Nasir K, Bittencourt M, Blaha MJ, Budoff MJ, Blankstein RB, Agatston A, Shaw LJ, Sibley CT, Blumenthal RS, Krumholz HM. Implications of Coronary Artery Calcium Testing Among Statin Candidates According to American College of Cardiology/American Heart Association Cholesterol Management Guidelines. J Am Coll Cardiol. 2015; 66:1657-68

28 April, 2016

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