Incidental Coronary Artery Calcium: Opportunistic Screening of Previous Nongated Chest Computed Tomography Scans to Improve Statin Rates (NOTIFY-1 Project)

Abstract

Background: Coronary artery calcium (CAC) can be identified on nongated chest computed tomography (CT) scans, but this finding is not consistently incorporated into care. A deep learning algorithm enables opportunistic CAC screening of nongated chest CT scans. Our objective was to evaluate the effect of notifying clinicians and patients of incidental CAC on statin initiation.

Methods: NOTIFY-1 (Incidental Coronary Calcification Quality Improvement Project) was a randomized quality improvement project in the Stanford Health Care System. Patients without known atherosclerotic cardiovascular disease or a previous statin prescription were screened for CAC on a previous nongated chest CT scan from 2014 to 2019 using a validated deep learning algorithm with radiologist confirmation. Patients with incidental CAC were randomly assigned to notification of the primary care clinician and patient versus usual care. Notification included a patient-specific image of CAC and guideline recommendations regarding statin use. The primary outcome was statin prescription within 6 months.

Results: Among 2113 patients who met initial clinical inclusion criteria, CAC was identified by the algorithm in 424 patients. After chart review and additional exclusions were made, a radiologist confirmed CAC among 173 of 194 patients (89.2%) who were randomly assigned to notification or usual care. At 6 months, the statin prescription rate was 51.2% (44/86) in the notification arm versus 6.9% (6/87) with usual care (P<0.001). There was also more coronary artery disease testing in the notification arm (15.1% [13/86] versus 2.3% [2/87]; P=0.008).

Conclusions: Opportunistic CAC screening of previous nongated chest CT scans followed by clinician and patient notification led to a significant increase in statin prescriptions. Further research is needed to determine whether this approach can reduce atherosclerotic cardiovascular disease events.

Registration: URL: https://www.

Clinicaltrials: gov; Unique identifier: NCT04789278.

Keywords: atherosclerosis; computed tomography angiography; coronary artery disease; electronic health record; primary prevention.

Figure 1.. Study Flow Diagram

Abbreviations: ASCVD: atherosclerotic cardiovascular disease; CAC: Coronary artery calcium; CT: computed tomography.

Figure 2.. The NOTIFY-1 Quality Improvement Project.

Abbreviations: ASCVD: atherosclerotic cardiovascular disease; CAC: coronary artery calcium; CT: computed tomography; DL: deep learning.

Figure 3.. Sub-group Analyses of Statin Prescription Rates at 6 Months

Abbreviations: anti-HTN: antihypertensive; CAC: coronary artery calcium; LDL: low density lipoprotein; Rx: prescription. This figure demonstrates results of the primary analysis, statin prescription rates at 6 months, stratified by key patient characteristics. For the ethnicity/race subgroup analysis, we first classified patients with Hispanic ethnicity. Among non-Hispanic patients, we made subgroups based on race. We excluded subgroups with fewer than 10 individuals across arms for confidentiality. There was no significant heterogeneity in the treatment effect across patient subgroups (Supplement Table S2). The statin prescription rate was 0% for patients in the usual care arm with LDL-C <100 mg/dL or with missing LDL-C. Testing for heterogeneity of treatment effect using continuous variables (for age, DL-CAC score, and time since last visit) are listed in Supplement Table S2.