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Index termsCoronary Artery AnomalyCoronary Computed Tomography AngiographyChest Pain
Anomalies of the coronary arteries are uncommon; the prev-alence ranges widely, from 0.285% in autopsies (1) to 5.64% in coronary angiography (CAG) (2). In recent coronary computed tomography angiography (CCTA) studies, the prevalence of coronary artery anomalies ranged from 0.8–5.79% (3-6). The wide range is caused by the use of various classification systems (2, 3, 7, 8) and patient selection bias according to imaging mo-dality. CCTA has become the apparent standard of reference for the evaluation of coronary artery anomalies with the introduc-tion of the multidetector row CT and the development of an electrocardiography (ECG)-synchronized scanning and recon-struction technique (9-14). In addition to its non-invasiveness, CCTA was revealed to be superior to conventional angiography in the detection of coronary artery anomalies (15-17). While
most people with coronary anomalies are asymptomatic, recog-nition of some coronary anomalies, particularly those associated with myocardial ischemia and sudden cardiac death, is impor-tant for patient management (18, 19). In this study, we deter-mined the prevalence of coronary anomalies on CCTA and eval-uated the relationship between coronary artery anomalies and chest pain at a single center in Korea.
MATERIALS AND METHODS
Patients
Between December 2006 and April 2013, 13236 CCTA scans were performed out at our institution. After excluding 560 cases of patients who underwent CCTA scans more than twice, 12676 CCTA patient scans were finally enrolled in the present study. The patients’ clinical symptoms and cardiovascular risk profiles
Original ArticlepISSN 1738-2637 / eISSN 2288-2928J Korean Soc Radiol 2015;72(4):207-216http://dx.doi.org/10.3348/jksr.2015.72.4.207
Received July 30, 2014; Accepted December 7, 2014Corresponding author: Doo Kyoung Kang, MDDepartment of Radiology, Ajou University School of Medicine, 164 World cup-ro, Yeongtong-gu, Suwon 443-721, Korea.Tel. 82-31-219-5849 Fax. 82-31-219-5862E-mail: [email protected]
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distri-bution, and reproduction in any medium, provided the original work is properly cited.
Purpose: To determine the prevalence of coronary anomalies using coronary com-puted tomography angiography (CCTA) and to evaluate the relationship between coronary artery anomalies and chest pain.Materials and Methods: A total of 12676 patients underwent CCTA scans at our institution between December 2006 and April 2013 using a 64-slice CT and a 128-slice dual-source CT. We determined the prevalence of coronary artery anoma-lies according to the classification system proposed by Greenberg. The presence or absence of chest pain with each coronary artery anomaly was also evaluated.Results: Coronary anomalies were found in 176 patients (1.39%) at our institute. Anomalies of origination, course, and termination were detected in 118 (0.93%), 28 (0.22%), and 30 (0.24%) patients, respectively. After the exclusion of 32 patients with combined heart disease, typical (n = 16; 11.1%) or atypical (n = 28; 19.4%) chest pain was present in 44 (30.6%) of the 144 patients at the time of diagnosis.Conclusion: The prevalence of coronary artery anomalies was 1.39% at our hospi-tal. After the exclusion of patients with combined heart disease, 11.1% had typical chest pain at the time of diagnosis.
Coronary Artery Anomalies: Assessment with Electrocardiography-Gated Multidetector-Row CT at a Single Center in Korea1
단일기관에서 심전도 동기화 전산화단층촬영에 의한 관상동맥 기형의 평가1
Boram Yi, MD1, Joo Sung Sun, MD1, Hyoung-Mo Yang, MD2, Doo Kyoung Kang, MD1 Departments of 1Radiology, 2Cardiology, Ajou University School of Medicine, Suwon, Korea
Coronary Artery Anomalies: Assessment with ECG-Gated Multidetector-Row CT at a Single Center in Korea
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a pitch of 0.2, a tube voltage of 120 kV, and an effective tube cur-rent of 600–900 mA with ECG modulation. Thereafter, 80 mL of contrast medium (Iomeron 400; Bracco, Milan, Italy) was intrave-nously injected at a rate of 4.5 mL/s, followed by a 40 mL saline flush at 4 mL/sec. Scanning was automatically initiated 6 sec after a threshold of 150 Hounsfield units (HU) was achieved in a re-gion of interest in the descending aorta. The 75% R-R interval was primarily used for image reconstruction. In cases of motion arti-facts, which reduce the diagnostic quality of images, additional cardiac cycles were explored for images of better quality. Trans-axial images (slice thickness, 0.9 mm; increment, 0.45 mm) were reconstructed using an ECG-gated half-rotation reconstruction algorithm and a sharp kernel (XCB filter).
Dual Source 128-Slice CT Scanner
CCTA was acquired using the retrospective ECG-gating spi-ral scan protocol and the following parameters: a detector colli-mation of 128 × 0.6 mm, a 280 msec gantry rotation, a temporal resolution of 75 ms, a tube voltage of 100–120 kV (according to the patient’s body mass index), and an effective tube current of 300 mA. The prospective tube current modulation technique was used with a high-dose window of 65–80% of the R-R interval (if heart rate > 75, then the window was between 35% and 50% of the R-R interval) and with the MinDose protocol (Siemens, Forchheim, Germany) in the remaining phases of the cardiac cycle. Contrast material was administered at an injection rate of 4.5 mL/s using a dual-syringe power injector (Stellant D; Me-dRAD, Indianola, IA, USA). The split-bolus protocol injection was used to inject contrast medium according to body weight. An injection of 60–80 mL of pure, undiluted iodinated contrast material (Iomeron 400; Bracco, Milan, Italy) was followed by a constant volume of 40 mL of a 60%:40% saline-to-contrast me-dium mixture. Scanning was automatically initiated 7 sec after a threshold of 100 HU was achieved in a region of interest in the ascending aorta. The patient table feed/pitch was variable (range, 0.17–0.38) and was adapted to the heart rate. Retrospective re-construction was automatically obtained (Best-Phase, Siemens) within in the maximum-dose time window based on the opti-mal diastolic phase-free motion artifacts. In cases where motion artifacts reduced the diagnostic quality of images, additional cardiac cycles were explored for images of better quality. Images were reconstructed using the following parameters: slice thick-
were obtained through a review of their respective medical charts at the time of the CCTA. We classified patients according to the characteristics of their chest pain as follows: typical, atypical, non-anginal, and no chest pain. According to American College of Cardiology-American Heart Association guidelines (20), typ-ical chest pain refers to 1) substernal chest pain or the ischemic equivalent discomfort, 2) provoked by exertion or emotional stress, and 3) relived by rest or nitroglycerin. Atypical chest pain is defined as chest pain or discomfort with two features of the above three characteristics of typical angina. Non-anginal chest pain is chest pain or discomfort that meets one or none of the typical angina characteristics (21). There was also a no chest pain group. We recorded the presence of other symptoms such as syncope, dyspnea, and palpitation in patients with no chest pain. Hypertension was defined as a systolic blood pressure of 140 mm Hg or greater, diastolic pressure of 90 mm Hg or great-er, or current antihypertensive treatment. Diabetes mellitus was defined as a confirmed diagnosis or the use of antidiabetic med-ication at the time of the study. Smoking was defined as those individuals who currently or previously smoked cigarettes daily. Dyslipidemia was defined as total cholesterol of at least 200 mg/dL or treatment with a lipid-lowering medication. Family histo-ry was defined as having a first-degree relative with a document-ed history of myocardial infarction or sudden cardiac death. The past history included a previous myocardial infarction or stroke. The outcomes were collected through a medical chart review and included coronary artery bypass graft, percutaneous coro-nary intervention, myocardial infarction, and sudden cardiac death. Our Human Research Committee approved the study design, and informed consent for the present retrospective anal-ysis was waived.
CCTA Image Acquisition
Image acquisition was performed using a Brilliance 64-slice CT scanner (Philips Medical Systems, Eindhoven, the Nether-lands) between January 2009 and February 2011 or a dual source 128-slice CT (Somatom Definition FLASH; Siemens Healthcare, Forchheim, Germany) between March 2011 and April 2013.
64-Slice CT Scanner
Retrospective ECG-gated CCTA was performed using a de-tector collimation of 64 × 0.625 mm, a 400 msec gantry rotation,
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tical analyses. All data are expressed as the mean ± standard de-viation. p < 0.05 was taken to indicate statistical significance.
RESULTS
Prevalence of Coronary Artery Anomalies
Coronary anomalies were found in 176 patients (1.39%) at our institute (Table 1). The mean age of patients was 53 ± 12 years (age range: 19–85 years). Male patients accounted for 69.9% (123/176) of the study population. Anomalies of the ori-gin of the coronary artery were detected in 118 patients (0.93%), including 14 cases of single coronary artery, 31 cases of high takeoff, 13 cases of multiple ostia of the left coronary artery (LCA), 57 cases of origin of a coronary artery from the opposite coronary sinus, and 3 cases of origin of a coronary artery from a non-coronary sinus. Anomalies of the course of the coronary artery were detected in 28 patients (0.22%). Anomalies of coro-nary artery termination were detected in 30 patients (0.24%), including 25 cases of coronary artery fistula and 5 cases of extra-cardiac termination. Coronary artery anomalies considered he-modynamically significant were detected in 86 patients (0.68%).
Relationship between Coronary Artery Anomalies and
Chest Pain
After excluding 32 patients with combined heart disease–14 with obstructive coronary artery disease, 15 with valvular heart disease, and 3 with cardiomyopathy–the clinical symptoms of the remaining 144 patients were evaluated. The clinical symptoms of patients included chest pain (n = 88), dyspnea (n = 18), palpita-tion (n = 11), and syncope (n = 3). Fifty-six patients had no symp-toms (n = 61). Among the 144 patients, 44 (30.6%) had typical (n = 16, 11.1%) or atypical (n = 28, 19.4%) chest pain at the time of diagnosis (Table 2). The coronary anomalies considered hemody-namically significant showed a higher incidence of typical or atyp-ical chest pain than the others [44.9% (31/69) vs. 17.3% (13/75), re-spectively; p < 0.001]. This finding did not change [21.7% (15/69) vs. 1.3% (1/75), respectively; p < 0.001], when the cases with typical chest pain were selected. Two (22.2%) of nine single cor-onary artery (Fig. 1), 10 (27.0%) of 37 cases of anomalous origin of a coronary artery with an interarterial course, and 3 (13.0%) of 23 coronary artery fistulas (Fig. 2) had typical chest pain at the time of diagnosis. In cases of anomalous origin of the right cor-
Volume rendering technique, maximum intensity projection, multiplanar reformation image analysis, and curve reformation images were conducted using a commercially available worksta-tion (EBW, version 4.5; Philips). An experienced radiologist (D.K.K.) evaluated the CCTA using Vitrea 2 (version 3.8.1; Vital Image, Minnetonka, MN, USA) between December 2006 and February 2011, or using Syngo Via (Siemens Healthcare) be-tween March 2011 and April 2013. We used the classification system proposed by Greenberg et al. (7), who divided coronary artery anomalies into anomalies of origin, anomalies of course, and anomalies of termination. A normal variant is a relatively unusual finding that is observed in > 1% of the same population. An anomaly is a morphologic feature seen in < 1% of the general population (2, 14). The prevalence of myocardial bridging is 15–85% (22) in pathologic analyses and 5.7–30.5% in CCTA (23-26). Therefore, we classified the myocardial bridge a normal variant and excluded it from the current study. The right coronary artery and conal branch arising separately from the right sinus of Valsalva occur in approximately 50% of the general population (27, 28). Therefore, we classified these anomalies as normal vari-ants and excluded them from the current study.
Statistical Analysis
Microsoft Excel 2007 (Microsoft Corp., Redmond, WA, USA) was used for data collection. We determined the prevalence of coronary artery anomalies according to the classification system proposed by Greenberg et al. (7). The incidence of chest pain with each anomaly was also evaluated. Coronary anomalies considered hemodynamically significant included a single coro-nary artery, coronary artery origin from the opposite coronary sinus with an interarterial course, and coronary artery fistula (18). The incidence of chest pain in the coronary anomalies con-sidered hemodynamically significant was compared with the oth-er anomalies using the χ2 test. For coronary arteries with an anomalous origin, the interarterial course was divided into high and low interarterial types (29) and the incidence of chest pain was compared using Fisher’s exact test. MedCalc (version 12.1.1.0; MedCalc Software, Mariakerke, Belgium) was used for all statis-
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while the remaining 37 did not require any interventional or sur-gical treatment of the coronary artery anomaly. Twenty-five pa-tients had a combined coronary artery disease and three had variant angina. Of the four patients who underwent stress nucle-ar imaging, two patients (one high takeoff, one coronary artery fistula) had ischemia, and the remaining two patients with a ter-mination anomaly had normal findings. There was no myocardi-al infarction or sudden cardiac death associated with a coronary artery anomaly.
DISCUSSION
Anomalies of Origin of the Coronary Artery
A single coronary artery is an extremely rare congenital anom-aly in which only one coronary artery arises with a single ostium from the aortic trunk. The incidence of this anomaly is 0.0024–
onary artery (RCA) from the left coronary sinus with an inter-arterial course (n = 44) (Fig. 3), there was no difference in typi-cal chest pain complaints between the high and low interarterial courses [30.8% (8/26) vs. 12.5% (1/8), respectively; p = 0.403].
The Prognosis of Patients with Coronary Artery
Anomalies
Table 3 describes the clinical characteristics of 125 patients for whom a clinical cardiovascular risk profile was obtained for the coronary artery anomaly groups with more than five cases. With regard to a past history of cardiovascular disease, three patients [one multiple ostia, one left anterior descending (LAD) duplica-tion, and one coronary artery fistula] had a stroke. The study followed 158 (89.8%) of the 176 patients for a mean of 4.8 ± 1.9 (range 1.5–7.9) years. Of the 39 patients who underwent CAG, two required transcatheter closures of a coronary artery fistula,
Table 1. Coronary Artery Anomalies Detected in Our Institute (n = 176)Classification Cases Prevalence (%)Anomalies of origin (n = 118) Single coronary artery (atresia)* 14 0.11
Single LCA 10 0.08 Single RCA 2 0.02 LCX atresia 2 0.02High takeoff 31 0.25 LCA 4 0.03 LCA and RCA 2 0.02 RCA 25 0.20Multiple ostia of LCA 13 0.10Origin from opposite coronary sinus 57 0.45 Prepulmonic course 2 0.02 Inter-arterial course* 47 0.37 High interarterial course 37 0.29 Low interarterial course 10 0.08 Trans-septal course 3 0.02 Retro-aortic course 5 0.04Origin from non-coronary sinus 3 0.02
Anomalies of course (n = 28) Duplication of LAD 28 0.22 Type 1 27 0.21 Type 4 1 0.01
Anomalies of termination (n = 30) Coronary artery fistula* 25 0.20 Pulmonary artery 18 0.14 Left ventricle 3 0.02 Left atrium 1 0.01 Right atrium 1 0.01 Coronary sinus 2 0.02Extra-cardiac termination 5 0.04
Note.—*Anomalies considered hemodynamically significant. LAD = left anterior descending, LCA = left coronary artery, LCX = left circumflex artery, RCA = right coronary artery
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Table 2. Relationship between Coronary Artery Anomalies and Chest Pain (n = 144)
ClassificationTypical
Chest Pain (n = 16)
Others (n = 128)
Total Atypical Chest Pain (n = 28)
Non-Anginal Chest Pain (n = 44)
No Chest Pain (n = 56)
Anomalies of origin Single coronary artery (atresia) (n = 9)* 2 7 3 1 3 (n = 98) Single LCA 2 5 2 3
Note.—*Anomalies considered hemodynamically significant.LAD = left anterior descending, LCA = left coronary artery, LCX = left circumflex artery, RCA = right coronary artery
Fig. 1. 63 years old male patient with atypical angina. A, B. Volume rendering technique and three-dimensional maximum intensity projection images show aplasia of right coronary artery (RCA) and collateral vessel from left circumflex artery (arrow). C. Coronary angiography shows left dominant coronary artery with RCA aplasia.
BA C
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coronary sinus, 0.09–0.11% for the LCA arising from the right coronary sinus, 0.32–0.67% for the left circumflex artery arising from the right coronary sinus or proximal branch of the RCA, and 0.11% for the LCA or RCA (or a branch of either artery) arising from a non-coronary sinus (6, 31-35). In this study, the prevalence was 0.45% for coronary arteries with an anomalous origin from the opposite and 0.02% for anomalous origin from the non-coronary sinus. An anomalous origin of the coronary artery from the opposite or non-coronary cusp can take one of the following four courses, depending on the anatomic relation-ship of the anomalous vessel to the aorta and pulmonary trunk: prepulmonic, interarterial (i.e., a course between the right ven-tricular outflow tract and aorta), retroaortic, or transseptal (36). Retroaortic, prepulmonic, and transseptal courses seem to be benign, while an interarterial course carries a high risk of myo-cardial infarction, sudden cardiac death, arrhythmia, and synco-pe (37). Therefore, the course is important clinically. Compres-sion of the coronary artery between the aorta and pulmonary artery is a possible mechanism for restricted coronary blood flow, particularly during exertion (38-42). Other possible mech-anisms of restricted coronary blood flow are an acute takeoff an-gle, slit-like ostium, and compression of the intramural segment by the aortic valve commissure (29, 38). In this study, however, only 27.0% of the cases with an interarterial course had typical chest pain. When the interarterial course is further divided into two subtypes; i.e., high and low interarterial courses, Lee et al. (29) reported a higher prevalence of typical angina (43% vs. 6%) in patients with a high interarterial course of anomalous origin
0.044% according to a database of coronary angiographies (30). The reported incidence was 0.26% in one CCTA study (4). Some of those patients develop typical angina during childhood or ad-olescence (7). In our study, the prevalence of a single coronary artery was 0.11%, and 22.2% of those patients had typical chest pain. Although most individuals with a single coronary artery have a normal life expectancy, patients are at increased risk of sudden cardiac death if a major coronary branch runs between the pulmonary arteries and aorta (i.e., interarterial course).
Anomalous origins of a coronary artery from the opposite or non-coronary sinus are classified into four recognized patterns. The prevalence in patients who undergo angiography or CCTA was found to be 0.03–0.17% for the RCA arising from the left
Fig. 2. 82 years old male patient with atypical angina. A, B. Volume rendering technique and coronary angiography show tortuous vessels arising from the proximal left anterior descending (black ar-row) and right coronary sinus (white arrow) and draining into pulmonary trunk. Multiple tortuous vascular structures passes anterior to the pul-monary artery and forms a network (*) before it enters the pulmonary trunk. C. Axial CT image shows the entry site (arrowhead) into pulmonary trunk.
Fig. 3. 57 years old female patient with typical angina. A. Volume rendering technique shows anomalous right coronary ar-tery (RCA) ostium from the left coronary sinus. B. Oblique sagittal multiplanar reformation image shows RCA (arrow) travels between aorta (Ao) and pulmonary artery (*).
BA
A B
C
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of the myocardium. A coronary artery fistula is defined as a congenital or acquired coronary artery abnormality in which blood is shunted into a cardiac chamber, the coronary sinus, su-perior vena cava, pulmonary artery, or pulmonary vein, bypass-ing the myocardial capillary network (45). It is observed in 0.05–0.25% of patients undergoing diagnostic CAG and 0.2–0.4% of congenital cardiac anomalies (46). The symptoms of cor-onary artery fistulas mainly depend on the severity of the left-to-right shunt. Myocardial perfusion might be reduced due to the hemodynamic steal phenomenon and this can lead to myocardi-al ischemia or infarction (47). If symptoms develop, patients present with dyspnea, fatigue, orthopnea, chest pain, endocardi-tis, arrhythmias, stroke, myocardial ischemia, or myocardial in-farction (46). In our series, the prevalence of coronary artery fis-tula was 0.20%, and 13.0% of the cases had typical chest pain.
The coronary arteries can have connections to extracardiac vessels, such as the bronchial, internal mammary, pericardial, anterior mediastinal, superior and inferior phrenic, and inter-costal arteries, as well as the esophageal branch of the aorta (7). Such communications become clinically significant if a condi-tion develops that redirects blood flow from the coronary sys-tem to an extra-cardiac vessel because the latter has a lower re-sistance to flow (48). In this study, the prevalence of extra-cardiac
of the RCA from the left coronary sinus. However, there was no significant difference (30.8% vs. 12.5%, p = 0.403) in the inci-dence of typical chest pain between the high and low interarteri-al courses in our data.
Anomalies of Course of the Coronary Artery
The reported prevalence of myocardial bridges ranges from 15–85% in autopsies and 0.5–2.5% in angiography (22). In a re-cent report using CCTA, the prevalence was found to be up to 30.5% (23-26). Therefore, myocardial bridges are considered normal variants rather than anomalies, and we excluded these cases from the present study.
Duplication of the LAD artery has been reported in 0.64–1.3% of the patients undergoing coronary arteriography (31, 32). In a recent ECG-gated cardiac multidetector computed tomography study, the incidence was 0.045% (43). Duplication of the LAD ar-tery usually consists of a short and a long LAD and is categorized into four subtypes (44). In our series, we encountered only type 1 and 4 duplication of the LAD artery. The prevalence was 0.22% and none of the patients had typical chest pain.
Anomalies of Termination
Normally, a coronary artery terminates into the capillary bed
imaging of anomalous coronary arteries. Eur Radiol 2004;
14:2172-2181
17. Karaca M, Kirilmaz A, Oncel G, Oncel D, Yilmaz H, Tamci B,
et al. Contrast-enhanced 64-slice computed tomography
in detection and evaluation of anomalous coronary arter-
termination was 0.04% and one case had typical chest pain.This study had several limitations. First, this report was a retro-
spective single-center study. Therefore, only limited clinical data were available. A multicenter prospective study of the incidence, clinical manifestations, and natural history of each anomaly and their respective treatments will greatly enhance our knowledge of coronary anomalies. Second, the study only considered the rela-tionships between coronary anomalies and chest pain, although some congenital coronary anomalies presented with other symp-toms, such as dyspnea, palpitation, or syncope (46). Third, wheth-er the origin of any chest pain was due to a coronary anomaly was not proven in all cases. In this study, however, patients with obstructive coronary artery disease, valvular heart disease, or cardiomyopathy, all of which can lead to chest pain, were exclud-ed. Non-invasive tests including echocardiography or radionu-clide myocardial perfusion imaging using either exercise or pharmacologic stress could help to evaluate the cause of the pain.
In conclusion, the prevalence of coronary artery anomalies was 1.39% at our hospital. After excluding patients with com-bined heart disease, 11.1% had typical chest pain at the time of diagnosis. Knowledge of the appearance of congenital coronary artery anomalies and their clinical significance are important for an accurate diagnosis and will facilitate better patient manage-ment in the future.
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