Background
Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare condition that can be difficult to diagnose by echocardiography alone. The purpose of this study was to describe the clinical and echocardiographic presentation of ALCAPA, create a set of critical echocardiographic diagnostic criteria, and report outcomes.
Methods
A retrospective review was conducted of all patients diagnosed with isolated ALCAPA at two major cardiac centers between 1990 and 2015.
Results
Of the 37 patients identified, only 54% presented in infancy. The anomalous coronary artery (CA) origin was clearly imaged in only 54% of echocardiographic examinations. However, other consistently identified echocardiographic markers were found, including left CA flow reversal (91%), collateral CA flow (85%), right CA dilation (81%), abnormal pulmonary artery flow (79%), mitral regurgitation (74%), left ventricular dysfunction (66%) and endocardial fibroelastosis (57%). Presenting echocardiograms had five of seven markers in 85% of patients. Left ventricular dysfunction was the most common marker in infants (89% vs 38%, P = .005); older children were more likely to have collateral formation visualized by color Doppler (100% vs 75%, P = .04). Following surgery, there were no early surgical deaths. The median follow-up duration was 10.3 years. At last follow-up, 92% had normal left ventricular function, 3% had moderate or worse mitral regurgitation, and 17% had required reintervention.
Conclusions
Echocardiographic markers can reliably identify ALCAPA; these markers vary with the age of presentation. Surgical outcomes are excellent, and most patients will recover left ventricular and mitral valve function.
Highlights
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An understanding of commonly identified echocardiographic markers is critical in making the diagnosis of ALCAPA using transthoracic echocardiography.
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Key echocardiographic markers for ALCAPA vary with age of presentation on the basis of the degree of coronary collateralization that has occurred.
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Surgical outcomes with direct coronary reimplantation are excellent, and most patients will recover LV function with reduction in MR.
Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a rare but clinically significant form of ischemic congenital heart disease, frequently resulting in myocardial dysfunction and heart failure within the first year of life. The anomaly occurs in roughly 1 in 300,000 children (0.5% of those with congenital heart disease) but remains one of the more common causes of pediatric myocardial dysfunction.
Patients with ALCAPA are generally unaffected during fetal life, as elevated fetal pulmonary vascular resistance and pulmonary oxygen content are sufficient to meet the demands of the fetal myocardium. As the fetus transitions to neonatal life, however, left coronary artery (LCA) perfusion pressure and oxygen content fall as flow patterns change and pulmonary vascular resistance drops. LCA perfusion and myocardial oxygen delivery become insufficient and left ventricular (LV) myocardium becomes dependent on collateral coronary artery circulation from the right coronary artery (RCA). Infants with inadequate coronary collateral arteries will initially present with subtle symptoms of poor cardiac output and irritability with feeding. As cardiac dysfunction worsens, infants and children will develop profuse diaphoresis, dyspnea, pallor, and failure to thrive. Ultimately, as myocardial ischemia leads to severe LV dilation and dysfunction, mitral annular dilation and papillary muscle scarring lead to worsening mitral insufficiency. LV failure leads to overt heart failure symptoms such as tachypnea, dyspnea, tachycardia, wheezing, and cough. Without correct identification and surgical correction, 90% of infants will die within the first year of life. In contrast, children with well-developed coronary collateral arteries can present later in childhood, as LV function is better preserved and heart failure symptoms do not develop.
Correctly identifying ALCAPA in a timely manner is important for patients, regardless of the age of presentation. Electrocardiography has long been a key clinical test in the diagnosis of ALCAPA, frequently showing pathologic Q waves in both leads I and aVL, but requires definitive imaging to confirm the diagnosis. Cardiac catheterization with angiography has traditionally been the imaging test needed for this diagnosis. However, as echocardiographic techniques have improved, echocardiography can provide diagnostic imaging without the need for more invasive imaging in ALCAPA. Although age-related differences in echocardiographic markers for ALCAPA have been described, no systematic review of the diagnostic echocardiographic findings in patients with ALCAPA has been published. The purposes of this study were to (1) review a multicenter experience of the diagnosis and management of ALCAPA, (2) assess echocardiographic findings that aid in identification of ALCAPA, and (3) describe the short- and long-term outcomes of surgical repair.
Methods
This was a retrospective review conducted at Children’s Hospital of Wisconsin in Milwaukee and the Children’s Hospital and Medical Center in Omaha, Nebraska. We identified all patients who underwent surgical repair for ALCAPA between 1990 and 2015 from the surgical databases at both institutions. A review of available mortality databases in the states of Wisconsin and Nebraska did not disclose additional cases of ALCAPA for this study. We excluded patients with additional structural cardiac abnormalities, including partial ALCAPA or anomalous origin of the RCA. Demographic data collected included gender, age, date of diagnosis, and surgery. The medical records were reviewed for presenting symptoms, diagnostic studies, surgical data, as well as data on long-term follow-up and reinterventions. All echocardiograms were independently reviewed by one of three study authors. From echocardiograms obtained at initial presentation (preoperative) and those obtained at the most recent follow-up, LV measurements including internal diameter in systole, internal diameter in diastole, and biplane ejection fraction (LVEF) by the Simpson method were obtained when possible.
All echocardiographic studies were assessed for a clear demonstration of coronary artery origins, RCA dilation (>2 mm diameter in infants, >3 mm diameter in children 1–6 years of age, and >4 mm in those >6 years of age; Figure 1 A), mitral valve prolapse, and evidence of LV endocardial fibroelastosis ( Figure 1 B). Color Doppler echocardiography was reviewed to assess the degree of mitral regurgitation (MR), presence or absence of prominent color flow signals within the ventricular myocardium (consistent with collateral coronary artery vessels; Figures 2 A and 2B, Videos 1 and 2 , available online at www.onlinejase.com ), direction of flow signals within the LCA ( Figure 2 C, Video 3 , available online at www.onlinejase.com ), and presence of diastolic flow signals within the main pulmonary artery as the LCA empties into the pulmonary artery ( Figure 2 D, Video 4 , available online at www.onlinejase.com ). Mitral insufficiency was categorized on the basis of vena contracta width (1 mm, trivial; 1–3 mm, mild; 3–6 mm, moderate; and >6 mm, severe) as well as jet area and was graded from 0 to 4 respectively (4 being severe). Indices of diastolic function or strain were not routinely or reliably assessed throughout the study period and therefore were not available for measure.
Statistical Analysis
Continuous variables are presented as medians and ranges, and all discrete variables are presented as percentages. Statistical comparisons were performed using the χ 2 and Fisher exact tests. The presenting symptoms and the incidence of echocardiographic markers of ALCAPA in preoperative echocardiograms were compared between children <1 and >1 year of age. A P value < .05 was considered to indicate statistical significance.
Results
Demographics, Presenting Symptoms, and Diagnostic Modality
We identified 37 patients (35% men) with ALCAPA who underwent surgical repair between 1990 and 2015. The median age at diagnosis was 10.5 months (range, 1.3–219 months). Of the 37 patients, 54% ( n = 20) presented at <1 year of age, and 65% ( n = 24) presented at <2 years of age. Twenty-one patients (57%) presented with signs of heart failure, including respiratory distress, activity or growth intolerance, or overt congestive heart failure. The next most common presentation ( n = 11 [30%]) was for a murmur evaluation, and three patients (8%) were found serendipitously (cardiomegaly on chest radiography) while being evaluated for noncardiac symptoms. Two patients (5%) presented with sudden cardiac arrest, with successful resuscitation. Among those patients <1 year of age, 16 patients (80%) presented with signs and symptoms of heart failure. The majority of children >1 year of age were identified by a murmur or serendipitously ( n = 10 [59%]), while only six patients (35%) presented with heart failure symptoms ( P = .008; Table 1 ).
| Presenting symptom | Age < 1 y ( n = 20) | Age > 1 y ( n = 17) | P |
|---|---|---|---|
| Congestive heart failure | 15 | 6 | .008 |
| Murmur/cardiomegaly | 4 | 10 | .02 |
| Cardiac arrest | 1 | 1 | — |
All patients underwent echocardiography at the time of presentation, and 19 of 37 (51%) were taken to surgery with echocardiography as the sole imaging modality. The remaining 18 (49%) underwent additional imaging using other modalities: coronary angiography ( n = 17) and cardiac magnetic resonance imaging ( n = 1). One patient (echocardiography-only cohort) had unrecognized ALCAPA at the time of surgery to address severe mitral valve insufficiency. Although the majority of patients came from center 1 ( n = 27 [73%]), there was not a significant difference between the institutions’ choice to send a patient to surgery without additional imaging (13 of 27 [48%] vs six of 10 [60%]). In the first decade of the study (1990–2000), 7 of 18 patients (39%) were diagnosed using echocardiography alone. After 2000, 12 of 19 patients (63%) were diagnosed using echocardiography alone. After 2005, all patients were diagnosed using echocardiography alone without additional imaging.
Echocardiographic Findings
Echocardiographic markers of ALCAPA found in the initial echocardiograms at presentation are summarized in Table 2 . Coronary artery origins were clearly visualized in 19 studies (54%), a finding that appeared to improve over time. From 1990 to 2000, the coronary artery origins were clearly seen in five of 16 patients (31%). From 2000 onward, the coronary artery origins were clearly seen in 14 of 19 patients (74%). Other markers of ALCAPA present, in order of incidence, included documented retrograde flow within the LCA (30 of 33 [91%]), intramyocardial color Doppler flow signals within the ventricular muscle indicative of collateral coronary vessels (28 of 33 [85%]), RCA dilation (25 of 31 [81%]), and presence of abnormal Doppler flow signals within the pulmonary artery (27 of 34 [79%]). Indirect markers of coronary insufficiency were also collated, included MR (26 of 35 [74%]), significant LV systolic dysfunction (defined as LVEF ≤ 45%; 23 of 35 [66%]), and presence of LV endocardial fibroelastosis (20 of 35 [57%]; Figure 3 ). There was no era effect noted in any of these markers. Most of the patients ( n = 28 [85%]) had five of the seven indicators present at the time of diagnosis ( Figure 4 ). Infants (<1 year of age) were more likely to present with LV systolic dysfunction ( n = 17 [89%] vs n = 6 [38%], P = .005), while children who presented at >1 year of age were more likely to present with identifiable collateral vessels by echocardiography (14 of 14 [100%] vs 14 of 19 [75%], P = .04). Although observed at a higher percentage in infants, mild or greater MR was not found to be statistically different between age groups (16 of 19 [85%] vs 10 of 16 [62%], P = .38; Table 3 ).
| Marker | Total studies reviewed | Positive finding | Sensitivity (%) |
|---|---|---|---|
| Visualization of coronary artery origin | 35 | 19 | 54 |
| Flow reversal in LMCA | 33 | 30 | 91 |
| Collateral coronary flow | 33 | 28 | 85 |
| RCA dilation | 31 | 25 | 81 |
| Abnormal Doppler signal in PA | 34 | 27 | 79 |
| Mitral valve insufficiency | 35 | 26 | 74 |
| LV systolic dysfunction (LVEF < 45%) | 35 | 23 | 66 |
| LV EFE | 35 | 20 | 57 |
| Variable | Age < 1 y ( n = 20) | Age > 1 y ( n = 17) | P |
|---|---|---|---|
| LVEF (%), mean ± SD | 30 ± 17 | 47 ± 15 | .005 |
| LV dysfunction (LVEF < 45%) | 89% (17/19) | 38% (6/16) | .005 |
| Presence of collateral vessels | 75% (14/19) | 100% (14/14) | .04 |
| More than mild MR | 85% (16/19) | 62% (10/16) | .38 |
| Visualization of coronary artery origin | 58% (11/19) | 50% (8/16) | .74 |
| Flow reversal in LMCA | 89% (17/19) | 92% (13/14) | ≥ .99 |
| RCA size (mm) | 2.5 ± 0.79 | 4.6 ± 1.9 | .0003 |
| RCA dilation | 76% (13/17) | 85% (12/14) | .66 |
| Abnormal Doppler signal in PA | 74% (14/19) | 87% (13/15) | .14 |
| LV EFE | 53% (10/19) | 62% (10/16) | .73 |
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