When a Calcium Score of Zero Is Not Zero Risk: Non-Calcified Coronary Plaque and Adverse Plaque Features on Coronary Computed Tomography Angiography

Abstract

Introduction: Coronary artery calcium (CAC) scoring estimates calcified atherosclerotic burden, but a CAC score of zero does not exclude non-calcified coronary plaque or adverse plaque characteristics.

Objective: To determine the prevalence of non-calcified coronary plaque and describe reported adverse plaque features among patients with CAC=0 undergoing coronary computed tomography angiography (CCTA).

Methods: This retrospective, single-centre descriptive observational study was conducted at the Peshawar Institute of Cardiology and included CCTA examinations performed from July 2023 to June 2026. Reports were screened to identify patients with a documented CAC score of zero. Imaging findings were extracted from existing CCTA reports, and clinical risk-factor summaries were manually calculated from hospital records. Results were summarised using descriptive statistics.

Results: Among 532 patients with CAC=0 (mean age 43.7 ± 11.1 years; 296 men, 55.6%), 510 (95.9%) had no reported coronary plaque and 22 (4.1%) had non-calcified plaque. Four plaque-positive patients had reported adverse plaque features, representing 18.2% of those with non-calcified plaque and 0.8% of the entire cohort. Qualitatively described low-attenuation / hypodense morphology and positive remodelling were each reported in two patients. Spotty calcification and the napkin-ring sign were not documented.

Conclusions: Non-calcified coronary plaque was reported in 4.1% of patients with CAC=0, and a small subset had reported adverse plaque features. CCTA can identify non-calcified atherosclerosis that is not captured by calcium scoring alone. These anatomical findings do not establish independent clinical predictors or subsequent cardiovascular event risk.