Prevalence and Prognostic Implication of Non-Calcified Plaque in Asymptomatic Population with Coronary Artery Calcium Score of Zero

BACKGROUND AND OBJECTIVES: Non-calcified plaque (NCP) identified by coronary CT angiography (CCTA) has been reported in up to 10% of individuals with coronary artery calcium score (CACS) of zero. However, clinical risk factors and the prognostic value of NCP in asymptomatic subjects with CACS of zero are unknown. SUBJECTS AND METHODS: The study population consisted of consecutive asymptomatic subjects (48±8 years, 57% men) who underwent CCTA from December 2005 to January 2008 as part of a general health evaluation. RESULTS: Among 4491 of overall asymptomatic individuals with CACS of zero, 313 subjects (7%) had NCP: 279 patients (6%) with non-obstructive and 34 (1%) with obstructive. In multivariable analyses, age, male gender, diabetes, hypertension, and dyslipidemia were significantly associated with presence of NCP (all p<0.05). During the median follow-up duration of 22 months (interquartile percentile: 18 to 28 months) of subjects with NCP (n=313) and age, gender, and CCTA date matched individuals without NCP (n=313), there was no clinical event including all-cause death nor composite outcome of cardiac death, myocardial infarct, unstable angina requiring hospitalization, and revascularization after 90 days from index CCTA in both groups. CONCLUSION: In the largest series of asymptomatic individuals with CACS of zero undergoing CCTA, age, male gender, diabetes, hypertension, and dyslipidemia were independently associated with NCP. However, a future risk of exclusive NCP in asymptomatic subjects with CACS of zero was negligible.