Influence of symptomatic status on the prevalence of obstructive coronary artery disease in patients with zero calcium score

Background: CAC has been used to predict obstructive CAD on invasive coronary angiography. However, it is unknown how the prevalence of obstructive CAD in patients with zero CAC is influenced by the presence or absence of chest pain. Methods: 210 consecutive patients referred for CAC and CorCTA were included in this analysis. Chest pain was defined based on the Diamond-Forrester classification. Results: 134 patients (64%) were symptomatic and 76 (36%) were asymptomatic. Seventy patients had negative (33%); 140 had positive CAC (67%). In the symptomatic group with zero CAC, 8.2% (4/49) had an obstructive, non-calcified plaque; of these, 3 were <45 years. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CAC in the symptomatic population for detection of obstructive CAD were 0.86 (0.66-0.95). 0.42 (0.33-0.52), 0.28 (0.19-0.39) and 0.92 (0.8-0.97), respectively (p = 0.007). No asymptomatic subject with zero CAC had obstructive CAD. Sensitivity, specificity, PPV and NPV of CAC in the asymptomatic population for detection of obstructive CAD were 1.00 (0.66-1.00), 0.32 (0.21-0.45), 0.18 (0.10-0.31) and 1.00 (0.80-1.00), respectively (p = 0.05). Optimal cut-points to predict obstructive CAD and AUC were significantly different in symptomatic versus asymptomatic subjects (91 and 0.78 vs. 296 and 0.89, respectively) (p=0.005). CAC performed much better in symptomatic patients >45 years compared to younger patients to exclude obstructive CAD (AUC: 0.83 vs. 0.5, p < 0.001; NPV = 0.98). Conclusions: CAC is better in asymptomatic compared to symptomatic subjects, especially in patients <age 45, to exclude obstructive CAD. Symptoms and age should be considered when interpreting CAC. (C) 2008 Elsevier Ireland Ltd. All rights reserved.