Association of coronary artery calcium score with qualitatively and quantitatively assessed adverse plaque on coronary CT angiography in the SCOT-HEART trial.
Level 3 - non-randomized controlled study
Post-hoc cohort analysis of randomized trial data with 5-year clinical follow-up
PubMed 34529050 · doi:10.1093/ehjci/jeab135
What was done
In this post-hoc analysis of the SCOT-HEART trial, 1,769 patients with stable chest pain underwent non-contrast computed tomography (CT) and coronary CT angiography (CCTA). Agatston coronary artery calcium score (CACS) was stratified into zero (0 AU), minimal (1–9 AU), low (10–99 AU), moderate (100–399 AU), high (400–999 AU), and very high (≥1000 AU). CCTA images were evaluated for qualitative adverse plaque features (positive remodelling, low-attenuation plaque, spotty calcification, napkin ring sign) and quantitative plaque burdens (calcified, non-calcified, low-attenuation, total plaque burden via Autoplaque). Five-year clinical outcomes (myocardial infarction) were tracked.
What was found
Of 1,769 patients, CACS was zero in 36%, minimal in 9%, low in 20%, moderate in 17%, high in 10%, and very high in 8%. Among patients with zero CACS, 14% had non-obstructive disease, 2% had obstructive disease, 2% had visual adverse plaques, and 13% had low-attenuation plaque burden >4%. Non-calcified and low-attenuation plaque burden increased significantly across zero, minimal, and low CACS groups (P < 0.001), but did not differ significantly across medium, high, and very high CACS groups. Forty-one patients experienced a myocardial infarction over 5 years; 10% of these occurred in patients with a baseline CACS of zero. CACS >1000 AU and low-attenuation plaque burden were the only independent predictors of myocardial infarction after adjusting for obstructive disease and 10-year cardiovascular risk scores.
Why it matters
A zero CACS is associated with a favourable prognosis, but it cannot rule out non-calcified plaque, high-risk low-attenuation plaque, or future myocardial infarction in symptomatic patients presenting with stable chest pain.
Limits
This was a post-hoc analysis restricted to symptomatic patients presenting with stable chest pain, so findings cannot be directly generalized to asymptomatic screening cohorts. The absolute number of myocardial infarction events was low (41 events). Specific effect sizes and confidence intervals for the multivariable prediction models were not reported in the abstract.
Cited by
- supports An individual can have a coronary artery calcium score of zero and still experience a heart attack due to non-calcified soft plaque.