Assessing the reliability of coronary artery calcium score in symptomatic patients: challenging the 'power of zero'

Background The concept of a zero coronary artery calcium (CAC) score has been associated with a favorable prognosis and a high negative predictive value for excluding obstructive coronary artery disease (CAD), commonly known as the "power of zero." However, this approach has certain limitations, such as its inability to detect non-calcified plaques. In this study, we aimed to investigate the prevalence of both obstructive and non-obstructive plaques in patients with a CAC score of zero. Methods We conducted a retrospective evaluation of symptomatic patients who had undergone coronary artery calcium scoring and coronary computed tomography angiography (CCTA) between January 2020 and December 2021 at our institution. Results Out of the 884 patients enrolled in the study, 516 were found to have a CAC score of zero. Among these patients, the mean age was 51.9±11.0 years, and 51.6% were male. Surprisingly, 81 patients (15.7%) with a CAC score of zero exhibited some degree of plaques, while 435 patients (84.3%) had no detectable plaques. Among those with plaques, 25 (4.8%) had mild plaques, 47 (9.1%) had moderate plaques, and 9 (1.7%) had obstructive plaques as revealed by CCTA. Further details on the severity and extent of plaques can be found in the figure. Conclusion Our study unveiled a significant number of symptomatic patients with a CAC score of zero who actually had atherosclerotic plaques. This finding challenges the notion of the infallible "power of zero" in symptomatic patients. While CAC scanning remains valuable for risk stratification, it should be acknowledged that relying solely on a CAC score of zero may overlook cases with underlying atherosclerotic plaques. As a result, clinical decision-making should involve a comprehensive assessment, and further investigation might be necessary to ensure an accurate diagnosis and appropriate management in symptomatic patients.