Unduly long left main (79 mm) coronary artery arising from right coronary sinus in a 64-year-old diabetic man

Abstract

Coronary artery anomalies are usually an incidental finding on coronary angiogram. Most of them are benign, although few of them are malignant which may cause sudden cardiac death. A 64-year-old diabetic, hypertensive man underwent coronary angiography for evaluation of exertional dyspnoea, and angina which revealed an anomalous left main coronary artery (LMCA) arising from right coronary sinus which was unduly long (79 mm) but free from any disease. To the best of our knowledge after extensive search in literature, this is the longest LMCA to be ever reported. The patient was managed conservatively.

Background

Morpho-anatomical feature of left main coronary artery (LMCA) along with its variations is important for interpretation of coronary angiogram and revascularisation. Its diameter and length are 3–6 mm and 10–15 mm, respectively. Although relatively short in length, functionally it is the most important vessel in entire coronary tree. After arising from left sinus of valsalva, it runs between pulmonary trunk and left atrial appendage which further continues as left anterior descending artery (LAD) after giving off left circumflex artery (LCx). Various anomalies have been described in relation to its length, origin and course. Here, we report a case of the longest LMCA (79 mm) reported so far arising from right sinus of valsalva as seen on conventional angiogram and multidetector computerised tomogram in a 64-year-old diabetic, and hypertensive man.

Case presentation

A 64-year-old man with diabetes, and hypertension for past 15 years was evaluated for exertional dyspnoea and occasional angina for past one and half years. He had a positive family history of premature coronary artery disease in his first degree relative. His vitals were stable at presentation, and other physical examinations were normal. ECG showed mild ST-T changes in precordial leads. Echocardiography revealed mild concentric left ventricular hypertrophy (LVH), grade II diastolic dysfunction and normal ejection fraction. Exercise stress testing was unremarkable as it was stopped because of dyspnoea. Coronary arteriogram was performed through right dorsal transradial route using 5F Tiger guiding (TIG) catheter (Terumo Optitorque) after proper consent. LMCA could not be cannulated from its usual site (left coronary sinus) suggesting its anomalous origin. However, it was selectively cannulated from right coronary sinus which was coursing up and after taking a sharp turn downward was bifurcating into lLAD and LCx artery (figures 1 and 2). Right coronary artery (RCA) was arising from right aortic sinus close to LMCA but could not be selectively cannulated as catheter was flipping into LMCA. All the three arteries were apparently free of any disease.

Figure 1.

Left main trunk dividing into left anterior descending artery and left circumflex artery (A—antero-posterior caudal view; B—antero-posterior cranial view).

Figure 2.

Left main trunk dividing into left anterior descending artery and left circumflex artery (A—left anterior oblique caudal view, B—right anterior oblique cranial view).

Investigations

To confirm anomalous origin and define course of LMCA and RCA, 128-slice CT coronary angiography was performed which revealed unduly long LMCA (79 mm; figure 3) having a pre-pulmonic course (figure 4). LAD was type-III as it was going up to apex of left ventricle before termination. RCA was arising separately from right coronary sinus and was non-dominant.

Figure 3.

Multidetector computerised tomogram coronary angiography showing unduly long left main trunk arising from right sinus of valsalva. The right coronary artery is showing its usual site of origin (A—left anterior oblique view; B—antero-posterior cranial view).

Figure 4.

Volume rendered reconstruction on multidetector computerised tomogram showing pre-pulmonic course of left main coronary artery (LAD—left anterior descending artery; LCx—left circumflex artery; RCA—right coronary artery).

Differential diagnosis

In the background of long-standing diabetes, exertional dyspnoea could have been angina equivalence. Increased left ventricular end diastolic pressure as a result of underlying diastolic dysfunction and mild LVH, endothelial dysfunction, microvascular dysfunction, spasm and abnormal pain perception could have been other reasons for his dyspnoea.

Treatment

He was managed conservatively with amlodipine 5 mg one time per day, losartan 25 mg one time per day, hydrochlorothiazide 12.5 mg one time per day and metformin 500 mg two times per day.

Outcome and follow-up

He was discharged in stable condition and is on regular follow-up.

Discussion

LMCA normally originates from superior part of left sinus of valsalva and traverses behind right ventricular outflow tract to bifurcate into LAD and LCx. Its origin from right aortic sinus is exceedingly rare with reported incidence of 0.017%.¹ Although exact definition is not available, short and long left main trunk are considered when it is <5 mm and >15 mm in length.² Long left main trunk is quite rare as only few cases have been reported so far. The maximum reported length of LMCA from its usual site of origin (left aortic sinus) is 61 mm³ while it is 56 mm when anomalously arising from right aortic sinus as described by Sinha et al.⁴ Although short left main trunk is associated with increased risk of arteriosclerosis, similar association with longer one is not described.⁵ Long and short LMCA are associated with right and left dominance, respectively.⁶ The finding in our case was contrary as it was left dominance despite being long left main trunk. Also, all coronary arteries were free of any disease despite the fact that patient has long-standing diabetes (15 years). Delivery of hardware may become a challenging issue during intervention of such a long left main trunk, although it was normal in our case. In that case, guiding catheters with strong backup support like Amplatz left or right, Voda right or Ikari right will be better options. One may also choose TIG catheter through transradial route to have stable backup support. To conclude, this is the longest reported LMCA arising from any aortic sinus to the best of our knowledge.

Learning points.

• Rarely left main coronary artery may arise from right sinus of valsalva.

• It is an incidental finding, and usually benign in nature, may sometime cause sudden cardiac death as a result of repetitive ischaemia because of inter-arterial course (between aorta and pulmonary trunk) causing its compression, acute take off angle and sharp turn when courses downward to run in front of right ventricular outflow tract leading to reduced flow.

• Coronary tree may remain free of any atherosclerosis in a patient with long-standing diabetes (>15 years).

• Long left main coronary artery may be associated with left dominance.

• CT coronary angiography should be done to describe anatomy and course of coronary artery, other anomalies and extrinsic compression of anomalous left main trunk between great vessels.