The reliability of coronary artery calcium score in symptomatic patients: Questioning the “power of zero”

Background and Aims: A zero CAC score has been associated with good prognosis and has a high negative predictive value for the exclusion of obstructive coronary artery disease (CAD); the so called “power of zero”. However, it has several limitations such as inability to detect non-calcified plaques. We aimed to investigate obstructive and non-obstructive plaque ratios in patients with a CAC score of zero. Methods: We retrospectively evaluated symptomatic patients who underwent CAC scoring and coronary computed tomography angiography (CCTA) between January 2021 and June 2021 in our institution. Results: Of the 196 patients enrolled to the study 107 had a CAC score of zero. Of those patients with a CAC score of zero the mean age was 51.7±10.7 years and 63.6% were male. Of the patients 72 (67.3%) did not have any and 35 (32.7%) had some degree of plaques. Of those 20 (18.7%) had mild plaques, 9 (8.4%) had moderate plaques, and 6 (5.6%) had obstructive plaques on CCTA. The severity and extent of plaques were shown on Figure. Conclusions: Our study showed a substantial number of symptomatic patients with CAC score zero had atherosclerotic plaques. As CAC scanning alone misses some cases “power of zero” should be questioned in symptomatic patients.