The natural history of napkin-ring sign by coronary computed tomography angiography

Introduction
Despite their significance, the prevalence and the incidence of vulnerable plaques in coronary arteries, as well as their natural history, remain poorly known.

Aim
To evaluate the prevalence, incidence and evolution of napkin-ring sign (NRS), and to establish factors associated with its presence, progression, or regression, in patients with suspected coronary artery disease (CAD).

Material and methods
The study is based on a single-center prospective registry. Eighty-nine patients with suspected CAD underwent two computed tomography angiography (CTA) examinations within an interval of at least 24 months. High-risk plaque was defined by the presence of a low-attenuation area adjacent to the coronary lumen, surrounded by a ring of higher attenuation – NRS.

Results
At the baseline 53 NRS were observed in 22 (25%) patients, 7 (8%) patients had single NRS and 15 (17%) had multiple NRS. After the follow-up period, there were 68 NRS in 32 patients. In 18 patients progression was observed with 23 additional NRS. Presence of single NRS and diabetes were independent predictors of NRS progression.

Conclusions
The number of NRS plaque tends to increase over time in patients with suspected CAD. The progression may be predicted by the presence of diabetes or single NRS.