Background and aims To determine whether epicardial (EAT) and paracardial adipose tissue (PAT) volume and attenuation are associated with high-risk coronary plaque features. Methods In subjects with suspected acute coronary syndrome (ACS) enrolled in the ROMICAT II trial, EAT and PAT volumes indexed to body surface area (BSA) and attenuation were measured on noncontrast coronary artery calcium score (CACS) CT. High-risk plaque features (napkin-ring sign, positive remodeling, low density plaque, spotty calcium) and stenosis were assessed on coronary CT angiography (CTA). The association of EAT and PAT volume and attenuation with high-risk plaque and whether this was independent of clinical risk assessment, CACS and significant coronary artery disease (CAD) was determined. Results Of 467 (mean 54±8 yrs, 53% male) with CACS and CTA, 167 (36%) had high-risk plaque features. Those with high-risk plaque had significantly higher indexed EAT (median 59 (Q1–Q3:45–75) cc/m2 vs. 49 (35–65) cc/m2, p <0.001) and PAT volume (median:51 (36–73) cc/m2 vs. 33 (22–52) cc/m2, p <0.001). Higher indexed EAT volume was associated with high-risk plaque [univariate OR 1.02 (95%-CI:1.01 – 1.03) per cc/m2 of EAT, p <0.001], which remained significant [univariate OR 1.04 (95%-CI:1.00–1.08) per cc/m2 of EAT, p=0.040] after adjustment for risk factors, CACS, and stenosis ≥50%. Higher indexed PAT volume was associated with high-risk plaque in univariate analysis [OR 1.02 (1.01 – 1.03) per cc/m2 of PAT, p <0.001], though this was not significant in multivariate analysis. At a threshold of >62.3 cc/m2, EAT volume was associated with high-risk plaque [univariate OR 2.50 (95%-CI:1.69–3.72), p <0.001)], which remained significant [OR 1.83 (95%-CI:1.10–3.05), p=0.020] after adjustment. Subjects with high-risk plaque had lower mean attenuation EAT (−88.1 vs. −86.9 HU, p=0.008) and PAT (−106 vs. −103 HU, p <0.001), though this was not significant in multivariable analysis. Conclusions Greater volumes of EAT are associated with high-risk plaque independent of risk factors, CACS and obstructive CAD. This observation supports possible local influence of EAT on development of high-risk coronary plaque.

ObjectiveTo systematically investigate the literature for the influence of sublingual nitroglycerin administration on coronary diameter, the number of evaluable segments, image quality, heart rate and blood pressure, and diagnostic accuracy of coronary computed tomography (CT) angiography.MethodsA systematic search was performed in PubMed, EMBASE and Web of Science. The studies were evaluated for the effect of sublingual nitroglycerin on coronary artery diameter, evaluable segments, objective and subjective image quality, systemic physiological effects and diagnostic accuracy. Due to the heterogeneous reporting of outcome measures, a narrative synthesis was applied.ResultsOf the 217 studies identified, nine met the inclusion criteria: seven reported on the effect of nitroglycerin on coronary artery diameter, six on evaluable segments, four on image quality, five on systemic physiological effects and two on diagnostic accuracy. Sublingual nitroglycerin administration resulted in an improved evaluation of more coronary segments, in particular, in smaller coronary branches, better image quality and improved diagnostic accuracy. Side effects were mild and were alleviated without medical intervention.ConclusionSublingual nitroglycerin improves the coronary diameter, the number of assessable segments, image quality and diagnostic accuracy of coronary CT angiography without major side effects or systemic physiological changes.Key Points• Sublingual nitroglycerin administration results in significant coronary artery dilatation.• Nitroglycerin increases the number of evaluable coronary branches.• Image quality is improved the most in smaller coronary branches.• Nitroglycerin increases the diagnostic accuracy of coronary CT angiography.• Most side effects are mild and do not require medical intervention.