I first learned of coronary artery calcium scoring (CACS) in 1995 when the first CT scanner that could perform this screening test came to Michigan. In the past 30 years, I have ordered tens of thousands of these simple tests that reveal whether any calcified plaque is present in the heart arteries. Nearly 10,000 research studies have demonstrated the power of this test for diagnosis and prognosis. Oddly, the uptake by primary care doctors, cardiologists, and insurance payors has been very slow.
Recently, a randomized study in primary care has shown the power of knowing the CACS.
A prospective, randomized, open-blinded end point clinical trial in 7 hospitals across Australia (between 2013 and 2020; the last date of follow-up was June 5, 2021). Asymptomatic people aged 40 to 70 years with a first-degree relative with CAD onset at younger than 60 years old or second-degree relative with onset at younger than 50 years old were recruited from the community.
Intermediate-risk participants underwent CAC scoring. Those with a CACS greater than 0 but less than 400 underwent coronary computed tomography angiography (CCTA) and were randomized to CAC score-informed prevention or usual care.
Follow-up CCTA was obtained at 3 years, with plaque volume measured by an independent core laboratory. The primary outcome was total plaque volume, with further analysis for calcified and noncalcified plaque volume.
This study included 365 participants (age, 58 years; 57.5% male); 179 in the CACS informed and 186 in the usual care groups.
Compared with usual care, the CACS informed group showed a sustained reduction in total cholesterol (-3 mg/dL vs -56 mg/dL for the CACS group) and LDL (-2 vs -51 mg/dL) cholesterol levels at 3 years, which was associated with a reduction in pooled cohort equation risk calculation (2.1% vs 0.5%).
Plaque progression was greater in usual care than CACS informed participants for total plaque volume (4.9 vs 15.4), noncalcified plaque volume (15.7 mm3 vs 5.6 mm3), and fibrofatty and necrotic core plaque volume (4.5 mm3 vs -0.8 mm3). These plaque volume changes were independent of other risk factors including baseline plaque volume, blood pressure, and lipid profile.
The combination of CACS with a primary prevention strategy in intermediate-risk patients with a family history of CAD was associated with reduction of atherogenic lipids and slower plaque progression compared with usual care.
These data support the use of CACS to assist intensive preventive strategies in intermediate-risk clinic patients.
It is amazing it has taken 30 years to see a study proving the power of giving a primary care physician the results of the CACS. Patients are more precisely diagnosed, and more meaningfully treated based on the results.
The fact the the artery outcomes were more favorable after sharing the CACS results with primary care is the reason we recommend at the Kahn Center a CACS scan for all patients over the age of 45.
