Pre-operative evaluation and mid-term outcomes of anomalous origin of the left coronary artery from the pulmonary artery based on left ventricular ejection fraction

Objective The purpose of this study was to evaluate the prognosis of patients with anomalous left coronary artery originating from pulmonary artery with varying cardiac function after surgical correction. Methods This was a single-center retrospective cohort study including 51 patients with anomalous left coronary artery originating from pulmonary artery, all of whom underwent surgery at our center. Results All 5 deaths occurred in the pre-operative low cardiac function group (n = 39). After corrected by body surface area, parameters such as left coronary artery, right coronary artery, left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and main pulmonary artery diameter, were lower in patients in the normal cardiac function group than in the low cardiac function group. The rate of collateral circulation formation was higher in the normal cardiac function group. The proportion of changes of T wave was higher in the low cardiac function group (P = 0.005), and the duration of vasoactive drugs (dopamine, milrinone, epinephrine, nitroglycerin.) was longer in the low cardiac function group. Left ventricular end-diastolic diameter, left ventricular end-systolic diameter, main pulmonary artery diameter, and left atrial diameter were smaller than those pre-operatively (P < 0.05). Left ventricular ejection fraction was higher than that pre-operatively (P = 0.003). The degree of mitral regurgitation in the low cardiac function group was reduced post-operatively (P < 0.001). Conclusion There was a significant difference between the pre-operative baseline data of the low cardiac function group and the normal cardiac function group. After surgical repair, cardiac function gradually returned to normal in the low cardiac function group. The low cardiac function group required vasoactive drugs for a longer period of time. The left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left atrial diameter, and main pulmonary artery diameter decreased and gradually returned to normal after surgery. The degree of mitral regurgitation in the low cardiac function group was reduced after surgery.


Introduction
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital heart disease with an incidence of 1 in 300,000 live births (1).It can cause mitral regurgitation (MR) and left heart dysfunction.If left untreated, the mortality rate in the first year of life is about 90% (2).
ALCAPA can be divided into two types based on whether collateral circulation are abundant or not: infantile and adult types.The infantile type lacks a well-developed collateral circulation from the right coronary artery, leading to early symptoms in infancy.The adult type rarely presents with early symptoms because of a well-developed collateral circulation.However, older patients still have varying degrees of myocardial ischemia, and 80% to 90% of patients are at risk of sudden death (3).In recent years, with advances in echocardiographic and surgical techniques, the mortality rate of ALCAPA has been reduced to a low level (4).Previous studies concluded that low left ventricular ejection fraction (LVEF) is an independent risk factor for death (5)(6)(7)(8)(9).However, the clinical characteristics and surgical outcomes of patients with low LVEF are unclear and have not been reported.
In this study, we aimed to investigate the clinical characteristics and mid-term effects of ALCAPA repair, especially in patients with low LVEF, by analyzing the clinical data of children with ALCAPA in our center.

Patients and methods
This was a retrospective study of consecutive patients who underwent ALCAPA repair at our center from 2011 to 2020.This study was approved by the Ethics Committee, and no individual consent was required.
Overall, 51 patients who were diagnosed with ALCAPA and underwent surgical correction at our hospital were included in this study.Medical records were reviewed, including the following data: baseline details, clinical assessments, surgical management, post-operative outcomes, and clinical assessments at regular follow-up.Clinical assessments included electrocardiogram (ECG), chest radiograph, transthoracic echocardiogram and enhanced cardiac CT scan.
An abnormal Q wave was defined as a duration of ≥0.03 s, depth extending beyond one-quarter of the height of the R wave in the same lead, or depth ≥3 mm in lead I, 2 mm in lead avL, and ST-segment depression referring to depression ≥0.05 mV.Echocardiographic parameters included left atrial diameter (LAD), left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD), main pulmonary artery diameter (MPAD), right ventricular outflow tract diameter (RVOT), and left ventricular ejection fraction (LVEF).
Based on pre-operative LVEF, patients were divided into two groups: low LVEF group (LVEF ≤55%) and normal LVEF group (LVEF >55%) (10).The degree of MR on echocardiography was defined as absent, mild, moderate or severe using the ratio of regurgitant jets to the left atrium.
Surgical strategies included coronary artery reimplantation, intrapulmonary baffle repair (Takeuchi procedure), coronary artery bypass grafting, and left coronary artery ligation.Hospital mortality was defined as death before discharge or within 30 days after surgery.

Statistical analysis
All analyses were performed with IBM SPSS Statistics Version 22 (SPSS, Inc., Armonk, NY, USA).Continuous variables were expressed as mean and standard deviation (SD) or median and interquartile range (IQR).Categorical variables were expressed as frequencies and percentages.Two-tailed P-values <0.05 were considered statistically significant.

Pre-operative data
The pre-operative data of ALCAPA were summarized in Table 1.Fifty one patients were enrolled and divided into two groups based on pre-operative LVEF: the low LVEF group (LVEF ≤55%, n = 39) and the normal LVEF group (LVEF >55%, n = 12).43.1% (n = 22) of the total patients were male, and 64.7% (n = 33) were younger than 1 year of age.The median age at surgery was 0.4 years in the low LVEF group and 3 years in the normal LVEF group (P = 0.011).

Cardiac surgery
All patients underwent coronary artery reimplantation except one patient in the normal LVEF group who underwent left coronary artery ligation because of a well-developed collateral circulation.There was no significant difference in the proportion of patients who underwent simultaneous mitral valvuloplasty in the two groups (P = 0.815).Cardiopulmonary bypass (CPB) time (184.38 ± 85.99 vs. 131.75± 55.98 min, P = 0.053) and aortic cross clamping time (72.64 ± 26.27 vs. 71.92± 35.71 min, P = 0.94) were also not significant between the two groups.

Mortality and post-operative complications
Hospital mortality was 9.8% (5 of 51).No patient died in the normal LVEF group.Three patients died of heart failure, and one of them received repetitive mitral valvuloplasty due to severe MR.One died of malignant arrhythmia and the other died of respiratory failure due to a severe pulmonary infection.All of them were post-operative death.
No complications occurred in the normal LVEF group.No patient required extracorporeal membrane oxygenation (ECMO) support post-operatively.Delayed sternal closure was present in 7 (13.7%)patients due to unstable perioperative hemodynamics.Chylothorax was seen in one patient (1.9%) and improved with conservative treatment.Arrhythmias were present in 6 (11.8%) patients, two of whom received temporary cardiac pacing.

Follow-up
The median duration of follow-up was 3 (2.6-3.3)years.The longest follow-up was 9 years.There was no late mortality in the normal LVEF group, while one patient died of accidentally fall 1 year after the procedure in the low LVEF group.In the low LVEF group, one patient underwent mitral valvuloplasty for severe MR and infective endocarditis 6 years after LCA implantation.LVEF in the low LVEF group returned to normal within a median time of 12 months (Figure 1).At the last follow-up, nine patients in the low LVEF group had moderate or severe MR and four patients in the normal LVEF group (p = 0.4743) with normal LV function.

Discussion
Misdiagnosis of ALCAPA patients of different ages frequently occurs due to lack of specificity in clinical presentation, ranging from asymptomatic to heart failure and sudden death.In our study, 27 patients (52%) had false initial diagnoses due to lack of specificity of clinical presentation.In the neonatal period, pulmonary vascular resistance is high and abnormal LCA is supplied by PA.Despite relatively low oxygen saturation, the effective perfusion pressure was high enough to exclude significant myocardial ischemia.
At 1 month after birth, pulmonary vascular resistance falls to normal level, so that LCA is supplied by coronary  after echocardiography, it should be confirmed by CT scan or angiography before cardiac surgery.In our study, the results of CT scans showed that the origin of the abnormal coronary artery was found in all patients.Therefore, cardiac enhanced CT scans are recommended for patients suspected of having ALCAPA.
In the current study, patients were divided into two groups based on pre-operative LVEF.The mean age of the low LVEF group was 0.4 years, most of which were infants, while the mean age of the normal LVEF group was 3 years, most of which were elderly patients.The normal LVEF group had more collateral circulation than the low LVEF group.This suggests that the cardiac function of ALCAPA patients is related to the collateral circulation.Low LVEF has been reported to be a risk factor for death in ALCAPA (5)(6)(7)(8).In-hospital mortality after ALCAPA repair has been reported to range from 0 to 16% (14-16).In our study, the hospital mortality rate after surgery was 9.8% (5/51), which is comparable to the results of other centers.The five patients who died belonged to the low LVEF group and the main cause of death was heart failure or respiratory failure, suggesting that low LVEF is a risk factor for death 30 days after surgery.Over time, the LVEF improved and was within the normal range in most of our patients.An improvement in LVEF was observed at 1 year postoperatively.Some studies suggest that this may be due to the restoration of blood flow to previously hibernating myocardium (8,17).
The primary treatment for ALCAPA is surgery, including coronary artery bypass grafting, coronary artery reimplantation, Takeuchi procedure and coronary artery ligation.The aim of surgery is to reconstruct the normal coronary artery system.With the accumulation of experience in coronary artery grafting during transposition of the great arteries, direct coronary artery reimplantation has become the first choice for ALCAPA (18,19).In the present study, all patients underwent coronary artery reimplantation except one in the  (20).The severity of MR has been reported as a risk factor for mortality and reoperation rates (5,7).Most studies have concluded that treatment of MR is effective in promoting early recovery of cardiac function after ALCAPA repair (8, 9), although controversies still exist.Approaches to mitral valvuloplasty include intermittent valvuloplasty and fibrous papillary muscle stripping.In our study, pre-operative echocardiography showed no difference in MR ratios between the two groups of patients.We performed simultaneous MV repair in 27 patients.There was a decrease in the ratio of moderate and severe MR at discharge compared to the pre-operative period.One patient died of heart failure due to worsening MR.During follow-up, 13 patients still had moderate or severe MR but LV function had been normalized, and one patient underwent a second mitral valvuloplasty for heart failure due to severe MR.These results suggested that not all MR improve gradually by restoring LV function.
Patients with ALCAPA have inadequate post-operative cardiac function due to the long duration of aortic clamping and ischemia-reperfusion during surgery.Our results showed that the perioperative duration of vasoactive drugs was longer in the low LVEF group than in the normal LVEF group, suggesting that the maintenance of LV function after ALCAPA repair depends mainly on the use of inotropes, diuretics and vasodilators.Pharmacological treatment of chronic heart failure should be maintained after surgery until LV function and size return to normal range.This is an important factor in improving long-term prognosis, especially in patients with low LVEF (21).Long-term survival rates for patients with ALCAPA are 86-100% (7,22).During the follow-up of this study, one patient in the low LVEF group died from accidentally fall, while the long-term survival rate in the normal LVEF group was 100%.

Conclusion
There was a significant difference between the pre-operative baseline data of the low cardiac function group and the normal cardiac function group.After surgical repair, cardiac function gradually returned to normal in the low cardiac function group.The low cardiac function group required vasoactive drugs for a longer period of time.The LVEDD, LVEDS, LAD, and MPAD decreased and gradually returned to normal after surgery.The degree of MR in the low cardiac function group was reduced after surgery.Low LVEF may be a risk factor for death 30 days after surgery.

Limitations
Our study has limitations.First, the study design was a retrospective cohort series and the number of patients was small.Second, different surgical management and ALCAPA repair techniques were not compared.Further studies with longer follow-up and larger case numbers will be performed in the future.
normal LVEF group who underwent left coronary artery ligation due to extensive collaterals around the pulmonary sinus.It remains controversial for treating MR at the time of ALCAPA repair