Copyright © Italian Federation of Cardiology. Unauthorized reproduction of this article is prohibited. Detection of left main coronary artery anomalous origin with low-dose multidetector computed tomography using prospective ECG gating Gianluca Pontone, Daniele Andreini, Erika Bertella, Sarah Cortinovis, Stefano De Martini, Margherita Pirondini, Franco Fabbiocchi, Antonio L. Bartorelli and Mauro Pepi J Cardiovasc Med 2011, 12:506–509 Keywords: coronary anomalies, effective dose, multidetector computed tomography, prospective ECG gating Centro Cardiologico Monzino, IRCCS, Department of Cardiovascular Sciences, University of Milan, Italy Correspondence to Gianluca Pontone, MD, Via C. Parea 4, 20138 Milan, Italy Tel: +39 02 58002574; fax: +39 02 58002287; e-mail: gianluca.pontone@ccfm.it Received 22 May 2009 Revised 15 October 2009 Accepted 4 November 2009 To the Editor. Congenital coronary anomalies (CCA) are observed in approximately 0.3–1.3% of patients under- going diagnostic invasive coronary angiography (ICA). 1–3 Most of the congenital coronary anomalies are generally asymptomatic and benign. However, when the course of the anomalous vessel is between the aorta and the pul- monary trunk, syncope, angina, acute myocardial infarc- tion or sudden death may occur. 4–6 For many years, ICA remained the gold standard for the assessment of CCA. Alternatively, transesophageal echocardiography, 7–9 contrast-enhanced electron beam tomography 10 and MRI were used for detecting CCA. 11 However, these noninvasive imaging modalities are limited by low temporal or spatial resolution. Recent reports indicate that multidetector computed tomo- graphy (MDCT) may not only visualize CCA but better defines, as compared with ICA, the origin and course of the anomalous vessel. 12–14 However, radiation exposure and the consequent cancer risk are reasons of concern and may limit widespread clinical application, particularly in young patients. 15 Recently, prospective ECG gating was developed as an alternative to retrospective ECG gating to reduce the effective radiation dose. 16–18 We report a case of anomalous origin of the left main coronary artery (LMCA) from the right sinus of Valsalva that was detected by MDCT using prospective ECG gating and low radiation exposure. A 66-year-old man was admitted to our hospital because of syncope during exercise. Cardiac risk factors were smoking, hypertension and hypercholesterolemia. Physical examination, ECG, chest X-ray and echocardio- gram were normal. Stress–rest myocardial perfusion scin- tigraphy revealed fixed inferior and lateral perfusion defects. To rule out coronary artery disease, the patient underwent MDCT. An initial unenhanced scan was performed for calcium score. Then a contrast MDCT examination was performed using a 64-slice scanner (LightSpeed VCT XT, GE Healthcare, Milwaukee, Wis- consin, USA) with prospective ECG gating. 19 The patient received a 90 ml bolus of high-concentration low-osmolar and nonionic contrast medium (Iomeron 400 mg/ml, Bracco, Milan, Italy). The scan parameters were: slice configuration 64  0.625 mm, gantry rotation time 450 ms, tube voltage 100 KVp, effective tube current 600 mAs. Image CT data sets were analyzed using dedi- cated software (Cascore Package and CardioQ3 Package, GE Healthcare, Milwaukee, Wisconsin, USA). For radi- ation exposure, the dose–length product (DLP) was measured in mGy  cm and the effective radiation dose was calculated as the product of DLP multiplied by a conversion coefficient for the chest (K ¼ 0.017). 20 Volume-rendering reconstruction showed the left main and right coronary artery (RCA) arising separately from the right sinus of Valsalva (Fig. 1a and b). The left main coursed between the ascending aorta and pulmonary trunk (Fig. 1c) and gave off the left anterior descending (LAD) and left circumflex (LCX) coronary arteries in their normal position. Multiplanar reconstruction showed that the left main had an acute take-off angle with a slit- like narrowing of the lumen (Fig. 1d). Moreover, com- pression of left main mid portion between the ascending aorta and the pulmonary trunk and a 55% stenosis of its distal segment were also demonstrated (Fig. 1d). Finally, short-axis and long-axis reconstruction of the left ven- tricle showed subendocardial hypo-attenuation of the middle and apical segments of the anterior interventri- cular septum and anterior wall suggesting subendocardial necrosis (Fig. 1e and f). The effective radiation dose of MDCT was 2.2 mSv. Two days later, the patient under- went ICA that confirmed the anomalous origin of the left main (Fig. 2) but was unable to define the course of the anomalous vessel and its spatial relationship with the ascending aorta and pulmonary trunk. Intravascular ultrasound (IVUS) confirmed the slit-like shape of the proximal left main and the moderate stenosis of its distal Research letter 1558-2027 ß 2011 Italian Federation of Cardiology DOI:10.2459/JCM.0b013e328334f474