Anomalous origin of the left circumflex coronary artery from the first diagonal branch presented as acute myocardial infarction.

Coronary artery anomalies are diagnosed in 0.6 to 1.5% of patients who undergo coronary angiography (CAG). They may present with life threatening conditions but are generally asymptomatic. Recognition and adequate visualization of the anomaly is essential for correct management of the condition. However, in some cases the exact orifice and course of an anomalous coronary vessel cannot be selectively identified by CAG. In this report, a 54-year-old man was admitted to the hospital with acute inferior myocardial infarction and had an anomalous origin of the left circumflex coronary artery (LCX) from the first diagonal branch (D1). In CAG, the right CAG showed no significant stenosis and fortunately we found an anomalous origin of the LCX from the D1. The course of LCX was precisely established by 64-slice multi-detector computed tomography.

Introduction

The incidence of coronary artery anomalies in a routine coronary angiography (CAG) series is between 0.6% and 1.5%.1) The ostium of an aberrant vessel may be difficult to identify in the diagnostic procedure, but recognition and adequate visualization of the anomaly is essential for appropriate patient management, especially in patients undergoing evaluation for percutaneous coronary intervention (PCI) and cardiac surgery.2)

This report describes the anomalous origin of the left circumflex coronary artery (LCX) from the first diagonal branch in a 54-year-old man, which presented as an acute inferior myocardial infarction.

Case

A 54-year-old man with hypertension and 30 pack-years smoking history presented with chest pain. The resting electrocardiogram was demonstrating ST-segment elevation in leads II, III and aVF. CAG showed no critical stenosis in the right coronary artery (RCA) and no visualization of the LCX. Initially, we considered total occlusion of ostium of the LCX but the guide wire could not bypass the site which usually exists in an ostium of the LCX. We then identified the small artery originating from the first diagonal branch with thrombolysis in the myocardial infarction flow grade 1 (Fig. 1A and B). After balloon angioplasty was accomplished for that artery and D1, its course was similar to that of the LCX (Fig. 1C and D). To trace the exact anatomical course of coronary arteries, 64-slice multi-detector computed tomography (MDCT) was performed. MDCT demonstrated an anomalous origin of the LCX coursed to the left atrioventricular groove from the first diagonal branch (Fig. 2).

Fig. 1

Coronary angiographic finding. A and B: coronary angiography shows the small artery (arrow) with TIMI flow grade 1 originating from the D1 (arrowhead). C and D: after percutaneous coronary intervention for the small artery, the coronary angiography reveals an anomalous origin of the LCX from the D1. A and C: left anterior oblique cranial view. B and D: left anterior oblique caudal views. TIMI: thrombolysis in myocardial infarction, LAD: left anterior descending coronary artery, LCX: left circumflex coronary artery, D1: first diagonal branch.

Fig. 2

64-slice multi-detector computed tomography demonstrates an anomalous origin of the LCX coursed to the left atrioventricular (AV) groove from the D1. LAD: left anterior descending coronary artery, LCX: left circumflex coronary artery, D1: first diagonal branch, LA: left atrium, LV: left ventricle.

Discussion

Coronary artery anomalies have been identified in 0.6 to 1.5% of coronary angiograms.1) Previous studies reported that LCX anomalies were the third most common coronary artery anomaly diagnosed by using CAG.3) A total of 71% of patients with LCX anomaly had significant stenosis of the proximal LCX and 11% had severe atherosclerosis in this vessel alone.4) The origin of the LCX from the right sinus of Valsalva or RCA is a relatively common anatomical variation1)5) and some cases reported the origin of the LCX from the pulmonary artery.6) However, an anomalous origin of the LCX from the first diagonal branch is a very rare congenital anomaly.

Since the variable clinical presentation and prognosis of coronary anomalies depends on the proximal course of the anomalous arising coronary artery in relation to the great vessels, early detection and exact delineation of their proximal course are crucial.2) Conventional CAG has traditionally been used to diagnose coronary anomalies but in some cases the exact origin of anomalous coronary vessels cannot be selectively identified by this technique.6)7) The three dimensional acquisitions of either MDCT or cardiovascular magnetic resonance allow unambiguous interpretation of the locations of coronary origins.6)7) For our patient, initially we recognized an anomalous origin of the LCX from the first diagonal branch by conventional CAG and finally the origin of the LCX could be precisely established by MDCT.