A comprehensive analysis of the intramural segment in interarterial anomalous coronary arteries using CT-angiography

Abstract Aim An anomalous coronary artery originating from the opposite sinus of Valsalva (ACAOS) with an interarterial course can be assessed using Computed Tomography Angiography (CTA) for the presence of high-risk characteristics associated with sudden cardiac death. These features include a slit-like ostium, acute angle take-off, proximal luminal narrowing and an intramural segment. To date, no robust CTA criteria exist to determine the presence of an intramural segment. We aimed to deduct new CTA parameters to distinguish an intramural course of interarterial ACAOS. Methods and results Twenty-five patients with an interarterial ACAOS (64% female, mean age 46 years, 88% right ACAOS) from two academic hospitals were evaluated. Inclusion criteria were availability of a preoperative CTA-scan (0.5-1mm slice-thickness) and peroperative confirmation of the intramural segment. Using multiplanar reconstruction of the CTA, the distance between the lumen of the aorta and the lumen of the ACAOS (defined as ‘interluminal space’ (ILS)) was assessed at 2mm intervals along the intramural segment. Analysis showed a mean ILS of 0.69mm±0.15mm at 2mm from the ostium. At the end of the intramural segment where the ACAOS becomes non-intramural, the mean ILS was significantly larger (1.27±0.29mm, p<0.001). Interobserver agreement evaluation showed good reproducibility (intraclass correlation coefficient 0.77, p<0.001). ROC-analysis demonstrated that at a cut-off ILS of ≤0.95mm, an intramural segment can be diagnosed with 100% sensitivity and 84% specificity. Conclusion The ILS is introduced as novel and robust CTA parameter to identify an intramural course of interarterial ACAOS. An ILS of ≤0.95mm is indicative of an intramural segment.