The reported incidence of a single coronary artery (SCA) ranges from 0.2–1.6% of the population undergoing coronary angiography.1 Many of these anomalies are found incidentally. Identification of these anomalies is especially important in patients with coronary artery disease or valvular disease who are to undergo surgery, in order to avoid complications during surgical manipulations because of their unusual nature. Furthermore, these anomalies are of clinical interest because they can cause cardiac ischemia, sudden death, congestive heart failure or cardiomyopathy even in the absence of coronary stenosis.2 While the most common anomaly is the abnormal take-off of the circumflex (CX) artery from the right coronary sinus or right coronary artery (RCA), a somewhat rarer anomaly is an abnormal origin of the RCA from the left coronary sinus.3,4 There is a well-known association between hypertrophic cardiomyopathy and an increased incidence of myocardial bridges.5 However, to our knowledge, an association between a coronary anomaly and non-obstructive cardiomyopathy has not been reported so far. This is the first case report that presents a very rare variant of an SCA, in which the RCA originated from the distal CX artery in a patient with non-obstructive hypertrophic cardiomyopathy. Case Report. A 38-year-old white female was admitted to our hospital for evaluation of chest pain and exercise dyspnea. She had a history of atypical chest pain for six years. The pain usually lasted 30–60 minutes and was sometimes associated with dyspnea and palpitation. She had a history of cigarette smoking for twenty years. Her blood pressure was 130/80 mmHg and the pulse rate was 80 beats/minute. Physical examination, otherwise normal, revealed the fourth heart sound on the apical region. On admission, electrocardiogram showed sinus rhythm with 80 beats/minute, 1 mm downsloping ST-segment depression in leads V4–V6 and T-wave changes in leads V1–V3. Echocardiography revealed asymmetric non-obstructive septal hypertrophy (interventricular septum, 2.1 cm; posterior wall, 0.9 cm) with impaired ventricular diastolic compliance (Figure 1). Holter monitoring was normal except rare ventricular premature beats. An exercise thallium test was normal at maximum theoretical heart rate. Coronary angiography was performed at 48 hours after her admission. Cardiac catheterization showed a left ventricular end-diastolic pressure of 16 mmHg and an ejection fraction of 0.65 with hyperdynamic pattern of contraction. No pressure gradient was observed between the left ventricle and the aorta in pull-back. The left coronary artery and its branches were normal in origin and distribution. The RCA appeared to arise from the atrioventricular branch of the CX artery, and it followed the course, retrogradely, of the normal RCA distribution. On flushing the right sinus of valsalva, there was no evidence of an RCA (Figure 2). No coronary stenosis was observed in any of the coronary arteries. The symptoms of the patient were attributed to the non-obstructive hypertrophic cardiomyopathy and a treatment with verapamil was prescribed. Discussion. SCA is a rare congenital abnormality characterized by a common origin of both the right and left coronary arteries from a single aortic ostium. The congenital absence of the ostium of the RCA with the origin of the RCA as a continuation of the distal CX artery is an extremely rare variant of the SCA. Its real incidence is unknown. Such anomalies are usually considered to be benign, although one might wonder whether the retrograde perfusion of the RCA territory is equivalent to that in a normal vessel. Anomalous origins of the coronary arteries have drawn interest because they might cause sudden death in some cases. Furthermore, SCA is sometimes associated with other congenital malformations such as transposition of the great vessels, coronary arteriovenous fistula or bicuspid aortic valve.6–8 Previous cases with this peculiar anatomy were reported without any specifications except one with coronary ectasia.9 To our knowledge, the association between the SCA and hypertrophic cardiomyopathy has not been reported. This is the first case report that deals with a very unusual variant of SCA with the RCA originating from the distal CX artery in a patient with non-obstructive hypertrophic cardiomyopathy. It is well known that patients with hypertrophic cardiomyopathy have a risk of sudden death even in patients who are unaware of the disease. It is presumed, but not established, that sudden death is due to a ventricular arrhythmia, although atrial arrhythmias may play a role in sensitizing the heart so that ventricular arrhythmias subsequently appear.10 According to literature review, it is also reported that coronary anomaly might cause sudden death.11 Therefore, the association of SCA and hypertrophic cardiomyopathy should be born in mind because of the possible further increased risk of sudden death.
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