Abstract 3409: Does Absence of Coronary Calcification Predict the Absence of Coronary Plaque or Significant Luminal Stenosis on 64-Slice Computed Tomographic Coronary Angiography?
Objectives: We aimed to determine the prevalence and severity of coronary artery plaque (CAP) by 64-slice computed tomographic coronary angiography (CTCA) in patients with zero and low coronary artery calcium (CAC) scores.
Methods: We reviewed imaging findings of 984 consecutive patients with no known CAD (299 self-referred and 685 referred by physicians for diagnostic reasons) who underwent standard CAC scoring followed by 64-slice CTCA. Patients were separated into three CAC groups for analysis: Zero (416 patients), Low (138 patients; men with scores 1–50 and women with scores 1–10), and High (all remaining 430 patients).
Results: Prevalence of any CAP detectable by CTCA was 6.5% in the Zero CAC group and was significantly higher in the Low CAC (65.2%) and High CAC (96.5%) groups (all groups differed, p < 0.001). The marked CAP prevalence increase in the Low CAC group, compared to the Zero CAC group, was due to increased frequency of both plaques occluding < 50% of lumen (56.5% vs. 6.0%, p < 0.001, see Figure 1⇓) and plaques occluding ≥ 50% of lumen (8.7% vs. 0.5%, p < 0.001).
Conclusions: In outpatients with no known CAD, a zero CAC score predicts low prevalence of any CAP and very low prevalence of CAP occluding ≥ 50% of lumen. However, any CAC score greater than zero is associated with a high CAP prevalence and nearly a 10% rate of plaques occluding ≥ 50% of luminal area. High CAP prevalence in low CAC patients suggests that pursuing dedicated assessments of cardiovascular risk in such patients may be justified.