Non-Gated Triple Flash Coronary Computed Tomographic Angiography in Patients with Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) presents a potential challenge when performing coronary computed tomography angiography (CTA). To date, there is no ideal protocol for CTA in patients with AF. We sought to design a protocol for single-heartbeat coronary CTA in patients with AF. METHODS: We enrolled 32 patients with AF and a very low probability of coronary artery disease who were referred for CTA to assess pulmonary vein anatomy for catheter ablation. A 256-slice scanner was used. Twelve patients underwent CTA using non-gated triple Flash (NGTF) consisting of three prospective electrocardiogram (ECG)-triggered helical scans with a built-in ECG simulator, while retrospectively gated helical (RGH) was used in 20 patients. Radiation dose, and a 4-point scale was used to assess coronary artery image quality between CTA scan modes. RESULTS: A total of 96 vessels were analyzed. The 4-point score showed no significant differences between the RGH and NGTF scans (2.9 ± 0.6 vs. 2.8 ± 0.8, respectively; p = 0.34). The number of coronary arteries with extensive blurring did not significantly differ between the protocols, and included four vessels (6.6%) in RGH vs. three vessels (8.3%) in NGTF (p = 0.5). Radiation exposure was significantly higher with RGH scans, with a dose-length product of 835 ± 146 mGy compared with 382 ± 35 mGy for NGTF (p < 0.0001). CONCLUSIONS: Single heartbeat NGTF CTA has comparable image quality and significantly lower radiation dose compared to RGH scans in patients with AF. Whether this protocol can be used in next-generation computed tomography scanners has yet to be determined.

Relation Between Epicardial Fat and Subclinical Atherosclerosis in Asymptomatic Individuals.

PURPOSE: Excessive quantity of epicardial adipose tissue (EAT) is considered a risk factor for coronary artery disease (CAD). There are limited data, however, on the relationship between the quality of EAT and CAD. We investigated the association between the density and volume of EAT and subclinical CAD defined by positive coronary artery calcification (CAC), using computed tomography (CT). MATERIALS AND METHODS: We reviewed 609 consecutive CT scans of patients with a mild to moderate risk for CAD to assess the EAT volume, which was measured manually by tracing the parietal pericardial sac on axial images. Fat density was recorded in mean Hounsfield units (HU), and CAC was measured using the Agatston method. RESULTS: The mean patients' age was 50±11 years, and 393 (64.5%) were men. Overall, CAC was present in 135 (22%) patients, of whom 97 (72%) were men and 38 (28%) were women. The mean EAT volume and density were 65±27 cm and -87.0±3.4 HU, respectively. Patients with CAC had significantly higher EAT volume (74±27 vs. 62±26 cm, P<0.001) and lower EAT density (-88±3 vs. -87±3.4 HU, P<0.001) compared with patients without CAC. Multivariate regression analysis showed that both EAT density (hazard ratio, 0.879; 95% confidence interval, 0.817-0.946; P=0.001) and EAT volume >100 cm (hazard ratio, 1.693; 95% confidence interval, 1.256-2.999; P=0.029) predicted the presence of CAC. CONCLUSIONS: Both the quality and quantity of EAT derived from noncontrast CT scan predict subclinical CAD, with lower density and higher volume of epicardial fat associated with higher CACs.

Visceral adipose tissue influences on coronary artery calcification at young and middle-age groups using computed tomography angiography.

PURPOSE: The purpose of the study was to evaluate the impact of excessive visceral adipose tissue (VAT) on subclinical coronary atherosclerosis and coronary artery calcifications (CAC) in young and middle-age groups using multislice computed tomography. METHODS: This study is a single center, cross-sectional study. Eligible patients (n = 159), who under the age of 61 years, with chest pain and mild to moderate probability to have coronary artery disease (CAD) were enrolled. Coronary calcium score and epicardial adipose tissue (EAT) were measured at the level of the left main coronary artery while VAT was measured at the level of the iliac crest. RESULTS: The average age was (48 ± 8 years). The mean VAT was (38 ± 21 cm(2)) with no significant difference between men and women (38 ± 22 vs. 37 ± 19 P = 0.8) respectively. Student's t-test analysis showed significantly higher VAT in patients with detectable CAC than patients with no CAC (48 ± 24 vs. 33 ± 18 P = 0.00002), respectively. Univariate regression analysis showed that VAT and EAT, are strong predictor for CAC (hazard ratio [HR] 1.034, 95% confidence interval [CI: 1.016-1.052]. P <0.001 and [HR] 1.344, 95% CI: [1.129-1.601] P = 0.001), respectively. CONCLUSION: Excessive VAT is significantly associated with positive CAC. VAT can strongly predict subclinical CAD in individuals at young and middle-age groups.