Abstract 13289: Yield of Screening for Coronary Artery Disease in Asymptomatic Male Singapore Armed Forces Employees Using Very Low Radiation Dose Coronary Computed Tomography Angiography
Background: Screening for coronary artery disease (CAD) among asymptomatic individuals using coronary computed tomography angiography (CTA) is controversial due to concerns about diagnostic yield, therapeutic implications, exposure to radiation and contrast. The Singapore Armed Forces (SAF) instituted a pilot screening program of ‘high risk' individuals using CTA. The aim of this study was to determine the diagnostic yield of a screening program for CAD amongst a selected group of asymptomatic individuals.
Method & Results: Men working for the SAF who were over the age of 40 years, had one or more conventional risk factor for CAD and/or abnormalities of the resting ECG were selected for coronary CTA. After baseline renal assessment, these individuals underwent imaging using a 256-slice dual source scanner. Pre-procedure oral beta blockade with atenolol (median dose 50 mg) was used in 93%. A low radiation “flash” protocol was used in 95%. Image quality was acceptable in 98%. A total of 48 SAF employees underwent screening CTA. Mean age was 45 years. Diabetes, hypertension, hyperlipidemia and smoking were present in 37.5%, 58.3%, 87.5% and 45.8% respectively. Median radiation dose was 0.84 mSv and contrast volume was 82 ml. There were no adverse events. Twenty four (50%) subjects had coronary plaque (calcified and/or non-calcified). A plaque >50% in severity was found in 14 (29.2%) subjects while a severe (>70%) plaque was found in 6 (12.5%) individuals. Two subjects (4.2%) had severe double vessel disease. A coronary calcium score (CCS) of zero was found in 29 (60.4%). Of these, 8 (27.6%) had non-calcified plaque which was significant (>50%) in 5 (17.2%) and would have been missed without contrast CTA. Those with identified disease were referred for further evaluation and intensification of medical therapy.
Conclusions: Screening for CAD with contrast CTA using a modern scanner in an asymptomatic population at risk appears to have high diagnostic yield at very low radiation exposure. This includes detection of significant (>50%) disease (almost one-third) as well as identifying plaque in those with normal CCS. Larger studies are needed to determine the applicability of such a screening program in a wider population as well as the impact of screening on prognosis.
- © 2011 by American Heart Association, Inc.