MI ALCAPA

Myocardial infarction associated with anomalous left coronary artery from pulmonary artery (ALCAPA) and double right coronary artery

A 54-year-old man was referred to outpatient department for abnormal echocardiography. Electrocardiogram showed atrial fibrillation and abnormal Q wave in V2 and V3 suggesting old myocardial infarction in anterior wall. The echocardiography showed dilated LV chamber size (LV end diastolic dimension = 62.8 mm) with thickened basal to mid septal wall and akinesia with wall thinning of anterior wall. On cardiac computed tomography angiography (CTA), right coronary artery (RCA) and left circumflex coronary artery (LCX) were originated from aorta, however, left anterior descending artery (LAD) was originated from MPA and double RCA were originated from RCC (Figure 1). The RCA and LCX have tortuous, diffuse ectasia, and they communicated with LAD from MPA via rich collateral channels (Figure 2). Coronary angiography (CAG) showed LCX from left coronary cusp (LCC) and double RCAs from right coronary cusp (Figure 3). CAG also showed collateral flow from LCX to LAD which flow into MPA, and collateral flow from double RCAs to LAD (Figure 4). The results of oximetry were as follows: LV 98.1%, Aorta 98.1%, MPA 77.5%, RA 66.2%, RV 69.9%. The ratio of (Qp/Qs) was 1.3. These findings suggested mild left-to-right shunt flow. Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) syndrome results in the ‘coronary steal’ phenomenon, in which a left-to-right shunt leads to abnormal left ventricular perfusion. Therefore, in spite of abundant collateral flow between RCA and LAD, myocardial infarction was developed in the patients. He will be scheduled to take operation for correction shunt flow.

ALCAPA is a rare congenital anomaly. High mortality (above 90%) of untreated patients died within the first 12 months of life. A few patients could survive into adulthood due to collateral flow. However, myocardial ischemia due to coronary steal phenomenon caused heart failure or sudden cardiac death.

Fig. 1. Cardiac CT scan revealed left circumflex coronary artery (LCX) arising from left coronary cusp, left anterior descending (LAD) artery arising from main pulmonary artery (MPA) (A), and two RCAs arising from right coronary cusp (B).

Fig. 2. Cardiac CT scan revealed collateral flow to LAD from LCX (A, open arrow) and flow from RCAs (B, open arrow).

Fig. 3. Coronary angiography (CAG) showed LCX (A) originated from left coronary cusp and two RCAs (B and C) from right coronary cusp, however could not visualize LA.

Fig. 4. CAG showed collateral flow from LCX to LAD, which flow drained into MPA through LAD (A), and collateral flow double RCAs to LAD, which flow drained into MPA through LAD (B and C).

References

1. Boutsikou M, Shore D, Li W, Rubens M, Pijuan A, Gatzoulis MA, Babu-Narayan SV. Anomalous left coronary artery from the pulmonary artery (ALCAPA) diagnosed in adulthood: Varied clinical presentation, therapeutic approach and outcome. Int J Cardiol 2018;261:49-53.