While low-dose coronary artery calcium scoring scans (CAC) using CT have been around for some time, their effectiveness and relatively low cost in assessing cardiac risk seems to be taking on a new life. Accumulated wisdom and several newer studies have added to the body of clinical knowledge about CAC. These newer studies have done much to further validate its effectiveness in assessing cardiac risk in certain population groups. Because of this, CAC is being increasingly adopted by the medical community and many hospitals as an excellent screening tool to identify potential patients at moderate to higher risk for coronary artery disease (CAD). This blog will highlight these new findings and conclusions with links to the published studies. We also present a case study of a CFA client hospital that has effectively adopted CAC as a means to build public awareness along with offering a low-cost opportunity for the local and regional public to access a well-coordinated cardiac screening program.
Here is a summary of some salient conclusions from past and more recent studies about CAC.
- Low-dose CT calcium scoring tests offer physicians an effective way to address patients whose risk for CAD is the “gray zone” or middle of conventional risk approaches such as the Framingham Risk Score or Pooled Cohort Equations. Calcium scoring allows physicians to have additional risk evidence to be able to convince patients at risk that, for example, statins and aspirin regimens are right for them beyond recommended diet and exercise strategies. The picture produced by CT scans, showing visible calcium deposits, can be very convincing to patients who may be reluctant to start a drug regimen.
- To date, CAC screening has been studied in 100,000 patients, including large prospective studies with 15-year follow-up. Additionally, there are in excess of 1,000 peer-reviewed articles on CAC from single-site studies, multi-facility cohorts, and randomized trials.
- Data from the PROMISE[i] trial concluded that CT calcium scoring predicted events just as well as functional testing (such as stress testing or nuclear scanning), at a much lower price, and was easier to use.
- Other studies, including MESA[ii] (Multi-Ethnic Study of Atherosclerosis, The Dallas Heart Study, and others have produced similar conclusions as the PROMISE study, and support increased usage of CAC as a viable risk-assessment strategy.
- The newly released ACC/AHA blood cholesterol guideline[iii], for the first time setting specific LDL targets, specifically identifies CAC as a viable and cost-effective method of identifying and tracking calcium deposits and visually incentivizing at-risk patients to aggressively treat high cholesterol levels.
- Many hospitals charge as little as $50 for a CT calcium score study. This is a subsidized price designed to be attractive to the population and reduce barriers to enrollment. A full CAD screening program is often offered for $99 to $150 (see case study below for components).
- The 2017 Expert Consensus Statement on CAC from the Society of Cardiovascular Computed Tomography summarizes the available data validating CAC in support of the US Preventive Services Task Force Recommendations Statement for Statin Use in the Primary Prevention of Cardiovascular Disease in Adults.[iv]
- Low-dosage CT can be used serially to show changes in calcium over time. Scans have shown the reversal of disease over time to patients who have made an aggressive commitment to diet, exercise and statin use. Some believe that serial CT scans to document calcium scores and interventional strategies will become common practice (and clinically justifiable to payers for reimbursement) in the near-term future.
A quick, non-scientific review of hospital websites by CFA shows that these types of programs are becoming increasingly common. The overall design of these programs, required screening components, and overall operation is straightforward and fairly easy to replicate by other facilities.
A Successful Regional Hospital Screening Program
CFA has been working with a regional hospital cardiac program to re-energize its program. The hospital has developed and implemented a very successful public awareness and cardiac screening program incorporating CT CAC and promoted through a comprehensive regional marketing program that uses radio and print media. From program inception in May 2018 until November 1, the program screened 724 patients along two tracks – a comprehensive cardiac screen protocol including a CAC scan and a CAC scan-only screening exam. The table below presents the actual number of patients screened in the 6-month period, their various levels of calcium scores and other vital statistics from the program. Note that the screening has resulted in a significant (and appropriate!) number of referrals for both physicians and the sponsoring hospital.
In this regional patient population, the percentage of patients needing further follow–up and/or study has been trending at 16-17% and those needing an intervention (PCI or CABG) at 3-4% respectively. A full screen for self-referring patients includes a risk evaluation, body composition/BMI, blood pressure evaluation, CT CAC scan, resting ECG, lipid panel, and hemoglobin A1C test, and is offered for $99. Physician referrals are accepted for CT heart scans only and is offered for $50. The CT scan is administered by Radiology and the non-cardiac portion of the scan read by radiologists. The CAC study is read by qualified hospital cardiologists. Critical to the success of any such program is widespread communication and endorsement among physicians and administration on the plans for the program and the role each participant is to fill. Basic to this premise is the support of the local and regional referring primary care physicians (PCPs) who will need to be educated on the efficacy and effectiveness of CAC. Communication and cooperation ensure that the maximum number of potential referrals are captured and that important feedback on both individual patient participation and overall program performance is enhanced.
As can be seen, CT calcium screening can be a highly effective screening tool at a very reasonable price. Virtually any hospital with the technical and clinical capability, involvement of trained and capable physicians and the will to succeed can develop a successful program that will enhance public awareness of coronary artery disease and the importance of early detection. One interesting finding emerging in some recent CAC studies is the ability of CAC to identify a sub-population of asymptomatic, low CHD risk individuals who have exceptionally high coronary calcium and, therefore, are at greater risk for serious coronary events. Please see the American Journal of Medicine article on this topic here.
If you are interested in learning more about cardiac screening programs, cardiac services strategic development, clinical service expansion and/or other programmatic needs for your cardiovascular program, please contact CFA at (949) 443-4005 or by e-mail at email@example.com.
[i] Matthew J. Budoff, et al., Prognostic Value of Coronary Artery Calcium in the PROMISE Study (Prospective Imaging Study for Evaluation of Chest Pain), Circulation, Vol. 136, No. 21, 2018.
[ii] Silverman, MG, et al., Impact of Coronary Artery Calcium on Coronary Heart Disease Events in Individuals at the Extremes of Traditional Risk Factor Burden; The Multi-Ethnic Study of Atherosclerosis. European Heart Journal, 2014 Sep 1;35 (33): 2232-41.
[iii] Grundy, Scott M., et al; AHA/ACC/AACVPR/AAPA/ACPM/ADA/AGS/APhA/ASCP/NLA/PCNA Guideline on the Management of Blood Cholesterol, Circulation, 2018; DOI 10.1161.
[iv] Hecht, Harvey, et al. Clinical Indications for Coronary Artery Calcium Scoring in Asymptomatic Patients: Expert Consensus Statement from the Society of Cardiovascular Computed Tomography; J. of Cardiovascular Computed Tomography, published online 24, January 2017, pgs. 157-158.