The prevalence of coronary artery anomalies is reported to be approximately 0.3% to 2% of the general population [1‐11]. Most of these anomalies are asymptomatic during life, and the prognosis is good. However, some of these anomalies are associated with syncope, ischemic heart disease, and sudden death [12‐17]. These anomalies are detected as incidental findings during coronary angiography or at autopsy. Conventional coronary angiography (CCA) is widely available and considered the gold standard diagnostic tool in coronary anatomy. However, CCA is invasive and not able to demonstrate all coronary anomalies in detail, especially complex ones with anomalous courses. Recent advances in computed tomography (CT) techniques, such as multidetector computed tomography (MDCT) scanners, allow noninvasive visualization of the origin and course of coronary arteries. The aim of this study was to evaluate the prevalence of coronary anomalies in consecutive patients who underwent MDCT coronary angiography at Ilsan Paik Hospital, Inje University College of Medicine in Korea.

Among the 8,864 patients, 103 (1.16%) had coronary anomalies in this retrospective study. Their mean age was 60 ± 13.7 years (age range: 23 to 88, male:female ratio = 67:36). The baseline clinical characteristics of the patients are shown in Table 1. Ninety (87.4%) patients had origin and distribution anomalies, and 13 (12.6%) had a coronary artery fistula (Table 2).

Origin anomalies were the most common abnormality, with the coronary artery originating in the opposite coronary sinus. Of these anomalies, the most common type was a right coronary artery (RCA) originating from the left sinus of Valsalva (LSV) (41 patients, 39.8%) (Figure 1). All these anomalies passed between the aortic root and the pulmonary artery (interarterial course). Thirty-five of these 41 patients showed significant luminal narrowing of the opening of the RCA. Of these, two patients underwent a coronary artery bypass graft, and one patient underwent an unlooping procedure.

The left main coronary artery originated from the right sinus of Valsalva (RSV) in one case (Figure 2). This case also showed an interarterial course. In five patients, the left circumflex artery (LCX) arose from the RSV (3 patients, 2.9%) or the RCA (2 patients, 1.9%). In all these cases, the artery passed behind the aortic root (retroaortic course) (Figure 3).

Ten (9.7%) patients had no left main coronary artery (LMCA) and a separate ostium of the left anterior descending coronary artery (LAD) and LCX from the LSV (Figure 4). In seven patients (6.8%), the RCA and conus branch showed a separate origin from the RSV. One patient had a single coronary artery arising from the LSV. The LMCA divided normally into the LAD and the LCX. This patient’s RCA existed as a continuation of the distal LCX, with a retroaortic course (Figure 5).

We found 17 (16.5%) high-takeoff coronary arteries. Five RCAs coursed between the aorta and the pulmonary artery, resulting in compression and narrowing of the RCA lumen (Figure 6); and six RCAs and seven coronary arteries had a normal angulation and course.

Duplication of the LAD was found in four patients. In all these patients, the long course of the LAD originated from the RCA. The LAD had numerous septal branches and travelled through the interventricular groove before terminating at the cardiac apex. One LAD originated from the normal site and travelled through the anterior cardiac border, following a similar course to the diagonal branches (Figure 7).

Coronary artery fistulas were detected in 13 (12.6%) patients. Among these patients, fistulas arising from the LAD to the pulmonary artery were the most common.

The prevalence of coronary artery anomalies in our patients was 1.16%. In the largest study (n = 26,595) conducted by the Cleveland Clinic Foundation in North America in 1990, the incidence was 1.3% (n = 1,686). The findings in our study are similar to those described in the literature (Table 3). Thereafter, several studies conducted in different countries reported similar results. To the best of our knowledge, this is the first study to investigate the prevalence of coronary anomalies in the general Korean population.

The etiology of coronary anomalies is uncertain. There is no definite inheritance pattern and no sex predominance. In a previous study, the most frequent coronary anomaly was the origin of the RCA from the LSV and an absent LMCA [2, 4, 7, 10], with a separate origin of the LAD and LCX [1, 3, 5, 6, 9]. In our population, the origin of the RCA from the LSV was also the most common coronary anomaly (39.8%, 41 of 103 patients). This is a clinically significant anomaly because the interarterial course between the pulmonary aorta and the aorta and the compression of the RCA ostium may induce myocardial ischemia or sudden death. Anomalous origins of coronary arteries, where the artery crosses over to the opposite sinus, show four patterns: (1) an anterior course anterior to the pulmonary trunk or the right ventricular outflow tract, (2) an interarterial course between the pulmonary artery and the aorta, (3) a septal course through the interventricular septum, and (4) a retroaortic course posteriorly between the aortic root and the left atrium [20]. Of these, the interarterial course is clinically malignant because it is strongly associated with sudden death, myocardial ischemia, congestive heart failure, and endocarditis. The exact pathophysiological mechanisms of myocardial ischemia have not been determined. Cheitlin et al. [12] reported that a left coronary artery (LCA) arising as a single or double vessel from the anterior sinus of Valsalva, where the LCA passed leftward and posteriorly between the aorta and the pulmonary artery, is associated with sudden death. The assumed mechanism of sudden death is ostial closure between the aorta and pulmonary artery and the squeezing of the ostium during exercise, with sudden interference in coronary arterial flow [21, 22]. In such cases, complicated cardiac surgery or interventions are needed. Three of these patients of anomalous origin of the RCA in our hospital underwent coronary bypass surgery or coronary unroofing surgery. To evaluate the risk posed by a coronary anomaly, it is very important to discriminate an interarterial course from other courses. CCA is usually unable to provide information on the complex anatomy of coronary anomalies. ECG-gated MDCT is not only a noninvasive diagnostic tool but also a precise instrument for delineating the exact origin and course of coronary anomalies using 3D reconstruction. In planning surgery or coronary angioplasty for coronary anomalies, MDCT provides a more accurate picture of the origin and course of the coronary vessels than CCA. The main disadvantage of MDCT is the high exposure to radiation. Compared with 64-MDCT, 320-MDCT has better temporal resolution, with faster image acquisition and a shorter scanning time, thereby decreasing the radiation exposure of patients. The 64-slice CT may expose patients to more radiation, which might be unacceptable when screening young symptomatic individuals with suspected coronary anomalies [23]. Therefore, the new 320-slice MDCT has the potential to become the technique of choice for noninvasive diagnosis of coronary anomalies.

In previous studies, a separate origin of the LAD and LCX arteries from the LSV was the most common anomaly, occurring in 30–60% of cases. In the present study, the incidence was 9.7% (10 of 103). A common cause of multiple ostia is the conus branch arising directly from the aorta rather than the proximal RCA. This anomaly was seen in seven (1.9%) patients in the present study.

A single coronary ostium is extremely rare. Shirani et al. [24] classified a solitary coronary ostium into 20 categories according to the location of this anomaly. In our study, only one patient had a solitary coronary ostium. A solitary ostium in the LSV normally occurs in the LAD and LCX, and the RCA exists as a continuation of the distal LCX, coursing to the posterior and right atrioventricular groove.

A coronary anomaly with a high takeoff or ectopic origin refers to a left or right coronary ostium, which arises more than 0.5 cm above the sinotubular junction rather than at the aortic sinus [25, 26]. This is a hemodynamically benign coronary anomaly and usually considered a normal variant, but it may cause difficulties in cannulation during coronary angiography and coronary artery bypass surgery [27].

Dual LAD is a rare coronary anomaly. Spindola-Franco et al. [28] described four variations of dual LAD. In type IV, the long LAD arises from the RCA and enters the distal anterior interventricular groove, whereas the short LAD originates from the LCA and ends high in the anterior interventricular groove. Four patients in our study had a type IV coronary anomaly according to Spindola-Franco et al.’s classification. However, the anomaly differed somewhat from their description. The long LAD arising from the RCA passed anterior to the pulmonary artery and travelled anterior interventricular grooves where it followed the course of a traditional distal LAD. Another long LAD originating from the LCA coursed and terminated in the anterior left ventricular wall, without reaching the apex.

Coronary artery fistulas refer to abnormal connections between one or more of the coronary arteries and the heart chamber or another blood vessel, such as the pulmonary artery, the coronary sinus, or the superior vena cava. Most coronary artery fistulas are small, do not cause any symptoms [29], and are clinically undetectable until echocardiography or coronary arteriography is performed for an unrelated cause. Small fistulas usually do not cause any hemodynamic compromise. However, larger fistulas can give rise to the coronary artery steal phenomenon, which leads to ischemia of the segment of the myocardium perfused by the coronary artery [30]. In our study, the most common fistula was a connection between the coronary artery and the pulmonary artery, and none of the fistulas resulted in clinical problems.

The prevalence of coronary anomalies in this study was similar to that of previous studies. Coronary anomalies are rare. However, as some types of coronary anomalies are clinically significant and sometimes life threatening, it important to recognize that they are detected in angiographic images. ECG-gated MDCT is a noninvasive technique, with high temporal and spatial resolution. The 3D images obtained with MDCT can be used to provide accurate angiographic information on the origin, course, and termination of coronary anomalies, which cannot be visualized with conventional coronary angiography. Understanding coronary anomalies can aid the physician in treatment planning.