Anomalous left coronary artery from the pulmonary artery (ALCAPA)

Case contributed by Dr Vinay V Belaval


Exertional chest pain.

Patient Data

Age: 40 years
Gender: Male


Right dominant coronary circulation.

ANOMALOUS ORIGINS / COURSE: There is an anomalous origin of the left main coronary artery (LMCA) from the posterior wall of the proximal main pulmonary artery (8.4 mm above the pulmonary valve level) – compatible with ALCAPA (anomalous left coronary artery from pulmonary artery).

LMCA trifurcates into left anterior descending (LAD), left circumflex (LCX) and ramus intermedius (RI) arteries.

Multiple arterial collaterals are noted between the left and right coronary artery systems, mainly between the diagonal & septal branches of LAD and acute marginal branch of RCA. Multiple arterial collaterals are also noted between RCA and LAD & LCX in the interventricular septum and in myocardium.

LEFT MAIN: LMCA measures 11.8 mm in diameter at the level of ostium and 2.7 cm in length. It trifurcates into LAD, LCx and ramus intermedius (RI).


Type: III

Proximal: dilated measuring 11.2 mm in diameter. No stenosis.

Mid and Distal: Normal

Diagonals: D1 is a good caliber, early branch measuring 7 mm in diameter. It is normal.



Proximal: Dilated measuring 7.3 mm in diameter. Courses posteriorly from origin to enter into the left AV groove.

Distal: Normal

Obtuse marginals: OM1 is normal.



Proximal: Fusiform aneurismal dilatation noted measuring 19 mm in diameter. It courses anteriorly and to the left to reach anterior to main pulmonary artery and then courses back to enter into right atrioventricular groove. No thrombus.

Mid: Dilated measuring 13.2 mm in diameter.

Distal: Fusiform aneurismal dilatation noted measuring 20 mm in diameter

Posterior descending: Two in number, ectatic and are normal.  

Posterolateral ventricular branch: Normal

Case Discussion

Anomalous origin of left coronary artery from pulmonary artery (ALCAPA) in an adult is accompanied by multiple collaterals with dilated, tortuous native coronary arteries. 

DIfferentials for dilated coronary arteries include coronary arterio-venous fistula, Kawasaki disease, and coronary cameral fistulas.

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