Repeat CT: Unraveling Plaque Changes in CAD With Elevated Lp(a)
New research suggests serial coronary CT angiography (CCTA) can provide novel insights into the association between lipoprotein(a) and plaque progression over time in patients with advanced coronary artery disease.
Researchers examined data from 191 individuals with multivessel coronary disease receiving preventive statin (95%) and antiplatelet (100%) therapy in the single-center Scottish DIAMOND trial, and compared CCTA at baseline and 12 months available for 160 patients.
As reported in the Journal of the American College of Cardiology, patients with high Lp(a), defined as at least 70 mg/dL, had higher baseline high-density lipoprotein cholesterol and ASSIGN scores than those with low Lp(a) but had comparable coronary artery calcium (CAC) scores and total, calcific, noncalcific, and low-attenuation plaque (LAP) volumes.
At 1 year, however, LAP volume — a marker for necrotic core — increased by 26.2 mm3 in the high-Lp(a) group and decreased by -0.7 mm3 in the low-Lp(a) group (P = .020).
There was no significant difference in change in total, calcific, and noncalcific plaque volumes between groups.
In multivariate linear regression analysis adjusting for body mass index, ASSIGN score, and segment involvement score, LAP volume increased by 10.5% for each 50 mg/dL increment in Lp(a) (P = .034).
“It’s an exciting observation because we’ve done previous studies where we’ve demonstrated the association of that particular plaque type with future myocardial infarction,” senior author Marc R. Dweck, MD, PhD, University of Amsterdam, the Netherlands, told theheart.org | Medscape Cardiology. “So, you’ve potentially got an explanation for the adverse prognosis associated with high lipoprotein(a) and its link to cardiovascular events and, in particular, myocardial infarction.”
The team’s recent SCOT-HEART analysis found that LAP burden was a stronger predictor of myocardial infarction (MI) than cardiovascular risk scores, stenosis severity, and CAC scoring, with MI risk nearly five-fold higher if LAP was above 4%.
As to why total, calcific, and noncalcific plaque volumes didn’t change significantly on repeat CCTA in the present study, Dweck said it’s possible that the sample was too small and follow-up too short, but also that “total plaque volume is really dominated by the fibrous plaque, which doesn’t appear affected by Lp(a).” Nevertheless, Lp(a)’s effect on low-attenuation plaque was clearly present and supported by the change in fibro-fatty plaque, the next-most unstable plaque type.
At 1 year, fibro-fatty plaque volume was 55.0 mm3 in the high-Lp(a) group vs -25.0 mm3 in the low-Lp(a) group (P = .020).
Lp(a) was associated with fibro-fatty plaque progression in univariate analysis (β = 6.7%; P = .034) and showed a trend in multivariable analysis (β = 6.0%; P = .062).