Prevalence and Predictors of Atherosclerosis in Symptomatic Patients with Zero Calcium Score

Rationale and Objectives: Absence of coronary artery calcium (CAC) in symptomatic patients is associated with a very low risk of adverse cardiovascular events. However, patients with zero CAC may have noncalcified plaques (NCP). In this analysis, we sought to determine the prevalence and predictors of NCP in symptomatic patients with zero CAC. Materials and Methods: Coronary computed tomography angiography (CCTA) was performed in 333 consecutive symptomatic patients (mean age 50 +/- 12, 65% males) with zero CAC and no known coronary artery disease (CAD). Pretest likelihood was estimated by Framingham risk score (FRS). Independent predictors of NCP were identified using multivariate logistic regression. Results: NCP was detected in 55 patients (17%) on CCTA, of which 6 patients (1.8%) had significant stenosis. In univariate analysis, patients with NCP were older (55 +/- 7 vs. 50 +/- 10 years, P = .009), with higher prevalence of hypertension (80% vs. 63%, P = .013). Using multivariate logistic regression, the independent predictors of NCP in this cohort were intermediate to high FRS (OR 2.3, 95%CI 1.3-4.1, P = .007), whereas baseline statin therapy was associated with lower prevalence of NCP (OR 0.38, 95%CI 0.17-0.89, P = .02). Conclusion: Our analysis shows that nearly one in five patients with zero calcium score has NCP and one in three patients with zero calcium score and intermediate to high FRS have evidence of NCP on CCTA. The prognostic value of NCP in these patients needs further evaluation.