Infantile dilated cardiomyopathy due to congenital left main coronary ostial stenosis

Abstract

Although a rare form of congenital heart disease, anomalies of the coronary arteries can present as heart failure in infants. The most common lesion is an anomalous left coronary artery arising from the pulmonary artery, but other abnormalities can present similarly. This case is an infant who is found to have left coronary ostial stenosis causing dilated cardiomyopathy.

Congenital anomalies of the coronary arteries are a rare form of congenital heart disease. They have been reported to present at any age of life. In an infant, coronary artery anomalies can present with cardiac ischaemia leading to dilated cardiomyopathy and resultant failure to thrive. We report on a rare case of congenital left main coronary ostial stenosis that is presented as failure to thrive.

Case

A 4-month-old male who was born at 34 weeks was transferred to our hospital after a 3-week stay at an outside hospital for failure to thrive. He was transferred due to parental request for a second opinion on having a gastrostomy tube placed. Echocardiography during his initial workup at the outside hospital showed mild dilated cardiomyopathy with a left ventricular ejection fraction of 49%. Medical treatment with enalapril and furosemide was initiated.

Upon transfer, repeat echocardiogram at our hospital revealed severe dilated cardiomyopathy with a left ventricular ejection fraction of 24%, moderate mitral regurgitation and a small pericardial effusion. The coronary arteries were noted to have originated from their appropriate sinuses. Family history was negative for cardiomyopathy. Milrinone was started and the evaluation process for candidacy for heart transplantation was started.

A week later, ST-segment elevation was noted on telemetry. Review of the initial echocardiogram was concerning for left main coronary ostial stenosis due to aliasing of the color Doppler signal at the left main coronary artery origin (Fig 1a and Supplementary video S1). The next day, computed tomographic angiography also showed left main coronary artery stenosis (Fig 1b). A troponin I was 1.33 ng/ml afterward and ST-segment elevation was noted on the electrocardiogram. For further characterisation of the anatomy and haemodynamic assessment, the patient was taken to the cardiac catheterisation laboratory where his pulmonary capillary wedge pressure was 15 mmHg and angiograms confirmed the diagnosis of severe left main coronary artery stenosis (Fig 2 and Supplementary video S2).

Figure 1.

(a) Echocardiogram in the parasternal axis view showing color Doppler aliasing in the left coronary artery origin. (b) Computed tomographic angiogram showing narrowing of the left main coronary origin. (c) This postoperative image from a PSAX view demonstrates a widely patent left coronary artery ostium with laminar flow by color Doppler.

Figure 2. Angiogram obtained during cardiac catheterisation.

*Indicates left coronary artery origin with narrowing.

The patient was taken to the operating room, severe congenital left main ostial stenosis was found. Repair was performed with a pericardial patch over the left main coronary ostium. His mitral valve was left unrepaired. The post-operative course was uncomplicated. An echocardiogram on post-op day 12, the day of discharge, showed objective improvement of left ventricular function with an ejection fraction of 44%. Left ventricular function continued to improve. At 4-year follow-up, the patient was growing well, was asymptomatic, and the left ventricular ejection fraction was 58%. The left coronary artery was widely patent (Fig 1c). He did exhibit moderate–severe mitral regurgitation and worsening left ventricular dilation, consideration is ongoing regarding the timing of returning to the operating room for mitral valve repair.

Discussion

Dilated cardiomyopathy caused by a congenital anomaly of the coronary vasculature in infancy can be caused by a normally positioned coronary origin that exhibits ostial atresia or stenosis, or, more commonly, can be caused by an anomalous coronary artery arising from the pulmonary artery.¹ This was a rare case of congenital left main coronary artery stenosis that led to significantly reduced left ventricular function and failure to thrive early in life.

Reports of left main coronary artery stenosis are often associated with other congenital anomalies, such as coarctation of the aorta, truncus arteriosus and supravalvular aortic stenosis.^2-5 Isolated left coronary ostial stenosis and atresia are more rare.^6-8 Both can present similarly with failure to thrive, angina that presents as irritability with feeding, and ischaemic cardiomyopathy in infancy, though multiple cases of initial diagnosis in older patients have been reported.

In an infant presenting with cardiomyopathy and coronaries arising from their appropriate sinuses, left main coronary ostial stenosis is an important diagnosis to consider. It requires a high index of suspicion and careful echocardiographic analysis. In this case, a second review of the initial echocardiogram was important in the initiation of further evaluation and ultimately, treatment. This strategy should be carefully considered when the clinical picture does not match findings from the echocardiogram. Laboratory and electrocardiogram findings are useful to increase the index of suspicion for coronary disease in these patients. Multimodality imaging with non-invasive computed tomographic angiography and invasive angiography should be considered. Prompt diagnosis is important as ischaemia is ongoing and the chance for myocardial recovery decreases as the length and severity of ischaemia increase.

Even when it is an isolated lesion, surgical revascularisation is indicated. This case demonstrates that successful repair of this lesion can lead to the return of normal cardiac function. There is no standard of care as there are so few reported cases of left main coronary ostial stenosis as an isolated lesion. The pericardial patch has proven to be an adequate means of repair, demonstrated by the fact that the patient’s left ventricular ejection fraction has remained stable over 4 years of follow-up. Other cases have been reported of patients presenting in early childhood with severe congenital obstruction of the left main coronary ostium. Three cases were repaired using an azygos vein graft or patch.¹⁰ The success in our case of the pericardial patch supports the use of direct ostial repair rather than coronary artery bypass grafting.