Double right coronary artery detected on coronary computed tomography angiography: A case report.

Double right coronary artery is a relatively rare coronary anomaly. In this case report we aim to increase awareness of the importance of recognizing such anomaly and a brief literature review of similar cases and possible high risk features. Computed Tomography is well recognized modality to detect coronary anomaly and in our case we demonstrated this as well.

Introduction

Computed Magnetic Resonant Angiography (CMRA) and Coronary Computed Tomography Angiography (CCTA) are commonly used diagnostic tools in Cardiology; and Anomalous coronary arteries are often identified. CCTA was found to be a valuable modality to characterize coronary anomalies; [1]. The incidence of coronary arteries anomalies was calculated to be around 0.24–1.3% out of 70,850 patients underwent coronary angiography in a large series. The commonest anomaly identified in this series was separate ostia of left anterior descending and left circumflex arteries [2]. Clinical significance and relation of coronary anomalies to adverse outcome remains unclear and frequently neglected. However relation to sudden cardiac death was studied and thought that the risk increases with left main coronary artery arising from the right aortic sinus of Valsalva with an inter-arterial course; in particular in association with any of high risk features: slit-like ostium, acute angle take-off, intramural coronary segment, and inter-arterial course [3]. Double right coronary artery is a rare anomaly 4, 5; in general benign, however when associated with bifurcation stenosis was linked to complete heart block [6]. In this report, we report a case of double right coronary artery diagnosed on CCTA.

Case report

A 55-year-old male who has been known to have Dyslipidemia for few years on regular treatment and follow up was seen in the clinic for chest pain described to be atypical. A clinical examination was unremarkable. A panel of investigations, asworkup tests, revealed a normal electro-cardiogram, normal cardiac enzymes levels, and his lipids profile showed significant reduction of Total Cholesterol and Low Density Lipoprotein (LDL) compared to the profile checked around 6 months before. As he was not fit to perform exercise electro-cardiogram test due to ankle injury for which he was advised to avoid exercise for long time; he was subjected to Myocardial Perfusion Scintigraphy: Tc99m – Tetrofosmin (Stress: 688 MBq; Rest: 705 MBq) and was stressed with adenosine (35.8 mg); this study showed a reversible perfusion defect involving the anterior and antero-septal segments of the myocardium; suggestive of ischemia involving the left anterior descending artery territory. In view of low risk to major ischemic cardiovascular event with atypical chest pain and the result of Myocardial Perfusion Scan, Patient was planned for Coronary Computed Tomography Angiography (CCTA) which showed a normal anatomy of left anterior descending and left circumflex artery with no significant disease in the distal LAD (Fig. 1) which indicates false positive Myocardial Perfusion Scintigraphy. A striking anomaly was seen as double coronary artery arising from different Ostia (Figs. 2 and 3). A decision to medically treat coronary artery disease in this patent was made and further diagnostic workup with coronary angiography thought to be not clinically indicated.

Fig. 1

Shows LAD and LCx.

Fig. 2

Shows Double RCA.

Fig. 3

Shows Double RCA.

CT scanning protocol

Patient underwent CCTA on Philips Brilliance 64 multi-slice CT (64 MSCT), (Philips Healthcare, Netherland). Calcium score was initially done 2.5 mm slice thickness and 25 mm table increment. The CCTA was done in a retrospective ECG-gated in both 40% and 75% phases of heart rate of 60 hrpm using bolus tracking (BT) technique. The acquisition parameters were (see Table 1):

Table 1

Shows CT scanning protocol used on Philips Brilliance 64 multi-slices computed tomography.

kV	120
mA	600
Thickness	0.9 mm
Table increment	0.45 mm
Rotation time	0.4 s
Reconstruction	iDose 2
Filter	Cardiac standard (CB)
Matrix	512

Discussion

Double Right Coronary Artery (RCA) was described as early as 1994 when Barthe et al. first reported this anomaly in a patient who was evaluated for episodes of syncope and found to have severe aortic stenosis and underwent preoperative coronary angiography [7]. Clinical relevance of this anomaly remained unclear in many cases reported subsequently. Identification coronary anomalies, especially prior to intervention, may be of great help to interventionists, and may further help in choosing the best revascularization strategy [8], double RCA was linked to serious conditions such ischemic cardiac events and arrhythmia in some reports 6, 9. Often, Diagnosis of double RCA is difficult on coronary angiogram sometimes to differentiate between double RCA and high takeoff of a large right ventricular branch [10]. CCTA is an acceptable modality to diagnose double RCA and to characterize anatomical features 1, 11. In our case we describe a double right coronary artery detected on CCTA with no evidence of atherosclerosis. We think this anomaly is, to the best of our knowledge, benign and has no high risk features reported to be associated with adverse events.