Silent Intruder: Unveiling Asymptomatic Anomalous Left Coronary Artery in Adulthood

INTRODUCTION

Also known also as Bland White Garland syndrome, anomalous left coronary artery from the pulmonary artery (ALCAPA) is an uncommon congenital cardiac defect that is typically diagnosed in early childhood. It is responsible for about 0.25–0.5% of congenital heart disorders and affects 1 in 300,000 newborns.^[1] The symptoms usually start to show up at about 3 months of age, and if they are not addressed with surgery, they often result in heart failure and death. Due to collateral blood flow from the right coronary artery (RCA), some people might not have any symptoms. In adulthood, they may experience mild to severe symptoms, such as angina, arrhythmias, heart failure, mitral valve leak, shortness of breath, and restricted exercise tolerance. We report a case of ALCAPA discovered incidentally in an adult female during routine medical assessment, emphasizing that due to effective collateral circulation, the condition may continue without symptoms.

CASE REPORT

A 35-year-old female patient presented for a routine check-up with occasional shortness of breath of New York Heart Association class II. The electrocardiography (ECG) did not exhibit any noteworthy alterations [Figure 1a]. The initial survey did not reveal any major regional wall motion abnormalities and has normal echocardiogram findings, including an ejection fraction of 60% and Grade 1 diastolic dysfunction. However, on detailed study, parasternal short axis (PSAX) view in ECHO showed some subtle features like turbulence originating from pulmonary artery (PA) (shown by arrow) into a small channel [Figure 1b]. We were unable to trace it exactly. With these findings in mind, we performed a coronary angiogram for further evaluation of positive stress test and to investigate ECHO findings.

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Figure 1:

(a) Electrocardiography with no significant ST-T changes. (b) Parasternal short-axis echocardiogram view depicts a small anomalous channel (red arrow) representing the left coronary artery draining from the pulmonary artery.

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During the angiogram, as we were initially unable to engage the left system, we resorted to engaging the right system, revealing retrograde filling of the entire left coronary artery [Figure 2a]. Unexpectedly, there was extravasation of dye into a major artery which was an uncommon finding in cases of tight left main lesions, suggesting a potential unusual origin of the left coronary artery (LCA). This extravasation of dye had given us a crucial clue, suggesting that this site of retrograde filling into the major artery could be in the PA. On further investigation with pigtail injection into the PA, we have confirmed that LCA is arising from PA [Figure 2b], that leads to the diagnosis of ALCAPA [Figure 2c]. Retrogradely, we had confirmed that the channel seen in parasternal short axis view PSAX view coming from PA has a left coronary artery. The patient was subsequently referred to the cardiothoracic and vascular surgery department. However, due to the patient’s asymptomatic status, they declined surgery and are currently under regular follow-up, maintaining a stable condition.

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Figure 2:

(a) Pigtail aortogram displays an empty left sinus with no coronary arteries originating from it. (b) Angiogram of the right coronary artery (RCA) reveals a significantly enlarged RCA with retrograde filling of the left coronary artery, draining into the pulmonary artery (PA). (c) PA angiogram showing partial filling of the left coronary artery (yellow arrow) due to competitive flow.

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DISCUSSION

The abnormal origin of a coronary artery from PA was initially reported by Brooks in 1882, but a comprehensive clinical description did not appear until 1933.^[2] ALCAPA is a rare congenital heart condition, affecting about 1 in 300,000 newborns and constituting 0.25–0.50% of cases of congenital heart disease.^[1] About 90% of patients die from myocardial ischemia and heart failure during the 1^st year if they are left untreated. Only about 18–25% of patients with this condition reach adulthood.^[3]

Abnormal placement of the coronary buds or abnormal rotation of the spiral septum that divides the truncus is the two embryological causes of coronary abnormalities.^[4] Pulmonary circulation changes following birth are the cause of the syndrome’s clinical presentation. The balance between ductus closure and collateral development determines outcomes. There was no need for collateral vessel formation before birth as the patent ductus arteriosus maintains equal pressures in the main PA and aorta, ensuring the normal myocardial perfusion. However, immediately after birth, high pulmonary circulation resistance allows flow from PA to the left coronary artery (LCA), perfusing the left ventricle and reducing the likelihood of symptoms in neonates. A few weeks to months after birth, as the ductus arteriosus shuts and pulmonary vascular resistance decreases, blood supply to the LCA ceases, relying on collaterals from RCA, with survival dependent on collateral development. Reduced PA pressure causes reversal of blood flow from LCA to the PA, leading to the steal phenomenon.^[5] This coronary steal can cause mitral insufficiency due to ischemia that affects the ventricular walls and papillary muscles, as well as insufficient oxygenation and overt ischemia in the left myocardial tissue, which can result in the left ventricular (LV) diastolic overload.

Due to restricted or missing coronary collateral flow, infants with ALCAPA frequently experience early myocardial ischemia, LV dysfunction, dilatation, and mitral regurgitation. They also frequently exhibit pallor, poor weight gain, rapid breathing, and an increased heart rate. When it comes to adults, the average age of presentation is 40.6 years.^[6] Continuous murmurs are frequently heard from collaterals, but they can also be exclusively systolic when pulmonary arterial hypertension persists. Rhythm disorders in adulthood caused by changes in the cardiac electrical conduction system may hide underlying myocardial ischemia and result in sudden cardiac death. Some people with ALCAPA may have normal LV systolic function but still have dyspnea due to diastolic dysfunction, increased LV end-diastolic pressure. Anomalies of the coronary artery can be life-threatening during or after severe exertion. The risk of sudden death appears to decrease after age 50. Our patient escaped the infantile stage probably due to adequate collaterals from RCA supplying LCA.

CONCLUSION

ALCAPA, a rare congenital heart condition, that often leads to high infant mortality and rarely shows symptoms in adults. Our case report demonstrates how ALCAPA can go years without exhibiting any symptoms. Even though the initial risk of sudden death decreases with age, the management of asymptomatic patients remains debatable, requiring specific individualized considerations and diagnostic confirmation before intervention.