Prevalence of occult coronary artery disease in asymptomatic subjects as detected on coronary CTA.

Abstract

INTRODUCTION: This study evaluated the prevalence of occult coronary artery disease (CAD) in asymptomatic subjects as detected on coronary CT angiography (CCTA) in a large private hospital in Melbourne. METHODS: This retrospective study looked at all CCTA performed between January 2011 and June 2015. Only asymptomatic subjects were included. Subjects with previous history of CAD were excluded. The CT scanner used was Siemens Dual Source Scanner. Obstructive CAD was defined as at least one coronary artery with 50% reduction in coronary luminal diameter. RESULTS: There were 418 asymptomatic subjects screened for occult CAD. Of these, 308 (74%) were male. The median age of the cohort was 58 years (IQR 52-64) and the median radiation dose in dose length product (DLP) was 119 mGy*cm (IQR 104-186) or 1.7 mSv. The median Agatston Calcium Score was 16.6 (IQR 0.8-133.3). Seventy-five subjects or 18% (95% CI: 0.14-0.22) of the cohort were found to have obstructive CAD. There were proportionately more male than female subjects with obstructive disease, 62/308 (20.1%) vs 13/110 (11.8%), respectively (p= 0.03). Of these with positive findings, 46 (11%) were single vessel disease (VD), 18 (4%) were dual VD, 10 (2%) were triple VD and one with isolated left main disease. CONCLUSION: A significant proportion of asymptomatic middle-aged subjects was found to have obstructive CAD when screened with CCTA. Their exposure to CCTA radiation dose was minimal. Hence, CCTA is a potential screening tool for detecting occult CAD in an at-risk yet asymptomatic population.