January 1, 2013Open Access
Prevalence and Prognostic Implication of Non-Calcified Plaque in Asymptomatic Population with Coronary Artery Calcium Score of Zero
Key Result
In asymptomatic subjects with a coronary artery calcium score of zero, the presence of non-calcified plaque was associated with a negligible risk of future cardiac events, with zero all-cause deaths observed over a median 22-month follow-up.
Study Design
Type
Cohort (n=4,491)
Multicenter
No
Structured PICO
Does the presence of non-calcified plaque on CCTA predict adverse clinical events in asymptomatic individuals with a coronary artery calcium score of zero?
P
Population
4,491 asymptomatic adults aged 35 to 75 years with a coronary artery calcium score of zero, followed for a median of 22 months to assess the prevalence and prognostic value of non-calcified plaque.
E
Exposure
Presence of non-calcified plaque (NCP) on CCTA
C
Comparator
Absence of NCP (matched by age, gender, and CCTA date)
O
Outcome
All-cause death and composite outcome of cardiac death, myocardial infarct, unstable angina requiring hospitalization, and revascularization after 90 days from index CCTAcomposite
The presence of non-calcified plaque in asymptomatic individuals with a zero calcium score is associated with traditional risk factors but carries a negligible short-term risk of adverse cardiovascular events.
Main Result
Absolute Event Rate: 0% vs 0%
Limitations
- Retrospective design in a self-referred health promotion center population, introducing potential selection bias.
- Influence of post-test medical treatments, coronary intervention within 90 days, or risk factor control was not considered.
- Use of a 90-day window to exclude downstream revascularizations might have excluded some non-downstream procedures.
- Topographic distribution of coronary plaques and various plaque assessment approaches were not included.
- Follow-up duration of 22 months may not be long enough to discriminate future risk in this low-risk population.
Abstract
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.