Cardiovascular Testing and Changes in Lipid-Lowering Therapy After Coronary Artery Calcium Scoring

Coronary artery calcium (CAC) scoring improves risk prediction in primary prevention and can lead to a reduction in atherosclerotic plaque progression via increased use of preventive therapies.^1,2 Although the 2014 EISNER (Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research) study found no increase in downstream testing in individuals undergoing CAC scoring, subsequent single-center studies suggested that CAC scoring may lead to increases in stress testing.^3,4 Although CAC scoring is increasingly recommended, no large-scale, contemporary assessments of real-world testing and treatment patterns after CAC scoring are currently to inform the implications of expanded use.

What is the clinical question being addressed?

What percent of commercially insured patients receiving CAC scoring receive follow-up angiography and stress tests, and what percent uptitrate statins?

What is the main finding?

Among CAC recipients, 7% underwent additional cardiac testing within 1 month, and statin use rose by 12.4%.

Methods

Our study utilized the Merative MarketScan Commercial Claims and Encounters and Medicare Supplemental and Coordination of Benefits database, which includes patients and dependents with employee-sponsored health plans and Medicare-eligible patients with employer-provided Medicare Supplemental or Medicare Advantage plans, from 2019 to 2022 (n = 37,649,243). Our study included all adults ≥18 years who underwent an outpatient CAC scan and with continuous insurance coverage from 3 months prior through 6 months after the scan (n = 22,168). We excluded those prior diagnosis of angina or coronary artery disease (n = 2,204), those with an International Classification of Diseases-10 diagnosis of angina (I20.x), shortness of breath (R06.0x), or chest pain (R07.1, R07.2, R07.8x, R07.9) associated with a health care visit ≤3 months of the scan (n = 4,865) or the CAC scan itself (n = 3,896), and those with same-day coronary computed tomography angiography (CCTA, n = 52).

We assessed the proportion of individuals who underwent subsequent CCTA, stress testing (electrocardiogram, nuclear, echocardiogram, or magnetic resonance imaging), invasive angiography, percutaneous coronary intervention, and coronary artery bypass graft by month for 6 months after the scan using Current Procedural Terminology codes. Statin utilization at baseline was determined by filled prescriptions within 4 months before the CAC scan, and new prescriptions post-scan were identified from pharmacy claims. All analyses were conducted using SAS version 9.4 (SAS Institute Inc). The study was exempt by the University of Texas Southwestern Medical Center Institutional Review Board.

Results

We included n = 11,151 patients (86.2% aged 40-65 years; median age 51 years; 49.9% female), among whom 76.3% had hyperlipidemia, 40.1% had hypertension, and 11.0% had diabetes.

Overall, 1,483 (13.3%) patients underwent invasive or noninvasive downstream cardiac testing within 6 months of CAC scan (Figure 1A). The percent of individuals who underwent stress testing or CCTA began to increase in the month prior to CAC scoring (1.6%), peaked the month after (7.1%), then declined to <1% per month at 3 months post-scan. In the first month after CAC scoring, stress electrocardiogram (3.4%) was the most common noninvasive test performed, followed by stress nuclear (1.9%) and stress echocardiography (1.6%).

Figure 1.

Percent of Patients Undergoing Cardiac Testing and Statin Utilization by Month Before and After Undergoing CAC Scoring

(A) Percent Patients that Undergo Cardiac Testing by Month. (B) Percent Patients With Statin Prescriptions by Month. Percentages were calculated as the number of patients with a new prescription or an existing prescription from the previous month, divided by the number of patients at risk. Patients at risk were defined as those with continuous coverage, excluding individuals hospitalized for myocardial infarction (n = 11,151 total from baseline through month 6). High-intensity statin was defined as rosuvastatin ≥20 mg/day or atorvastatin ≥40 mg/day. CAC = coronary artery calcium; CT = computed tomography; EKG = electrocardiogram; MRI = magnetic resonance imaging.

Invasive angiography was performed in n = 48 patients (0.43%) in the first month following CAC scoring, n = 43 (0.39%) in month 2, and declined thereafter to 0.25% (n = 28) in month 3, 0.15% in month 4 (n = 17), 0.06% in month 5 (n = 7), and 0.13% (n = 15) in month 6. By the end of month 6, 158/11,151 (1.4%) patients had undergone invasive angiography, of whom 31/158 (19.6%) underwent percutaneous coronary intervention.

Within 1 month after CAC scoring, statin utilization increased from a baseline of 20.7% to 33.1%, while high-intensity statin use increased from 5.4% to 10.4% (Figure 1B).

Discussion

In a relatively young, commercially-insured population, 7% of patients who had a CAC score underwent additional cardiac testing in the following month. This is slightly lower than what has been reported previously, potentially due to the younger age of this population.⁵ The frequency of noninvasive testing began to increase slightly in the month prior to the CAC score, potentially indicating that either noninvasive testing is triggering CAC testing and/or providers are ordering multiple tests simultaneously. Importantly, invasive angiography use was infrequent after CAC testing, and revascularization was even rarer. Within 1 month, there was also an absolute increase in statin use by 12.4%, an over 50% relative increase from baseline, and high-intensity statin use doubled, consistent with prior studies that CAC scoring may lead to improved preventive medication utilization.¹ Although CAC scores are useful to determine statin initiation, 1 in 5 individuals undergoing CAC testing were already on a statin; reasons for CAC testing in this population deserve further exploration.

Our study is limited by the constraints of claims data. First, given we used commercial claims data, data are only available for CAC scans that were submitted to insurance, not those where patients pay out-of-pocket. Secondly, although we attempted to exclude symptomatic individuals, those who underwent stress testing may still have been symptomatic. CAC results may have led patients or doctors to reconsider symptoms previously attributed to other causes, or triggered patients to report previously undisclosed symptoms. Thus, whether these tests were or were not indicated is beyond the scope of this analysis. That there was not a corresponding large increase in coronary revascularization procedures provides reassurance that CAC testing is not leading to a substantial increase in nonguideline-based coronary revascularization. Third, we do not have the results of the CAC scores, so cannot determine the rate of testing in those with and without significant CAC. Lastly, as this was a younger population, global rates of testing after CAC scoring may be greater in older or higher-risk populations. A strength of this study is that the data represent patients from across a multitude of health systems, not just a single center.

Our data further highlight the potential for CAC scoring to increase uptake of statin therapy at a population level. The small observed increase in noninvasive testing following CAC scoring in contemporary practice is reassuring that CAC scoring utilization is broadly consistent with guideline recommendations for its use to guide preventive therapies rather than prompt additional testing.

Funding support and author disclosures

This project was in part funded by the University of Texas Southwestern Medical Center National Institutes of Health Clinical and Translational Science Award grant 1U54TR002361. Dr Navar reports research funding to her institution from Amgen and Esperion, and consulting fees from Amgen, Arrowhead, AstraZeneca, Bayer, Eli Lilly, Esperion, Janssen, Merck, New Amsterdam, Novartis, Novo Nordisk, Pfizer, Roche, and Silence Therapeutics. Dr Joshi reports grant support from Novo Nordisk, Amgen, Kaneka, Novartis, and Eli Lilly and consulting from Novartis, Kaneka, and New Amsterdam. Dr Nguyen was supported by an National Institutes of Health/National Heart Lung and Blood Institute T32 postdoctoral training grant (5T32HL125247-10). Dr Rohatgi reports research support from Cleerly, Quest, Labcorp, CSL Behring, Inc, consulting support from Raydel, and research grants from National Heart Lung and Blood Institute. Dr Peterson reports research funding to his institution from Amgen and Esperion. This study was determined to be exempt by the University of Texas Southwestern Medical Center Institutional Review Board. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.