Ann Thorac Surg 2010;90:2023-2027. doi:10.1016/j.athoracsur.2010.06.130
© 2010 The Society of Thoracic Surgeons
Original Articles: Pediatric Cardiac
Do High-Risk Infants Have a Poorer Outcome From Primary Repair of Coarctation? Analysis of 192 Infants Over 20 Years
Jonathan G. McGuinness, PhDa,
Yahya Elhassan, MB, BCha,
Sim Yee Lee, MB, BCha,
Lars Nolke, FRCSIa,
Paul Oslizlok, FRCPIb,
Kevin Walsh, FRCPIb,
J. Mark Redmond, MDa,
Alfred E. Wood, FRCSIa,*
a Department of Cardiothoracic Surgery, Our Lady's Childrens Hospital, Crumlin, Dublin, Ireland
b Department of Cardiology, Our Lady's Childrens Hospital, Crumlin, Dublin, Ireland
Accepted for publication June 23, 2010.
* Address correspondence to Dr Wood, Professor Eoin O'Malley National Centre for Cardiothoracic Surgery, Mater Misericordiae University Hospital, Eccles St., Dublin 7, Ireland (Email: jmcguinness2{at}rcsi.ie).
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Abstract
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Background: Balloon angioplasty for infant coarctation is associated with a high recurrence rate, making operative repair the gold standard for low-risk infants. Debate exists as to whether high-risk infants might be better served with primary angioplasty. We compared the outcome in high-risk versus low-risk infants over 20 years, in a center that always used surgical repair as the primary intervention.
Methods: Of 192 infants from 1986 to 2005, 56 were considered "high-risk," defined as requiring prostaglandin infusion together with either epinephrine infusion for 24 hours preoperatively, or ventilation and milrinone infusion for 24 hours preoperatively. All high-risk patients had a period of ventricular dysfunction prior to surgery, ranging from mild to severe. Outcomes were compared using Bonferroni comparison of means or the Fischer exact test as appropriate.
Results: Although the high-risk patients were smaller (3.3 ± 0.1 vs 4.2 ± 0.2 kg, p < 0.01), younger (18 ± 4 vs 57 ± 7 days, p < 0.01), and more often required a concomitant pulmonary artery band (25% vs 15%, p = 0.05), their cross-clamp times were the same as the low-risk patients (18.9 ± 0.9 vs 18.0 ± 0.4 minutes, p = 0.27) and there was no difference in postoperative morbidity(7% vs 3%, p = 0.11). However, there was a trend toward higher perioperative mortality(7% vs 2%, p = 0.07). When compared with the published studies of primary angioplasty in comparable high-risk infants, the mortality rate in our surgically treated high-risk group is much lower. Additionally, only 11% of our high-risk group required reintervention, with two-thirds treated successfully with a single angioplasty at 3.8 ± 2.2 years later, far lower than recurrence rates with primary angioplasty.
Conclusions: We propose that primary surgical repair of coarctation in infants who are high risk should be the primary treatment, with angioplasty reserved for recurrent coarctation.
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Introduction
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Primary angioplasty and stenting is now overtaking surgery as the treatment of choice for isolated coarctation in adults and older children, as recurrence rates are comparable if not superior to surgery. However, the pathology of coarctation is more complex in infants due to the common involvement of a hypoplastic arch and ductus arteriosus. This accounts for the high recurrence rate with primary angioplasty in infants. Generally, primary operative repair is considered the gold standard for low-risk infants as it has a low recurrence rate, allows for arch growth, and most modern series report a very low mortality rate. In recent years some cardiologists have suggested that high-risk infants might be better served with primary angioplasty and subsequent delayed definitive intervention [1–3]. High-risk patients are those who are duct dependent, have ventricular dysfunction due to excessive afterload, or have multiple organ dysfunction due to poor distal perfusion. These patients require optimization with prostaglandins, and inotropes or ventilation prior to intervention for coarctation. In our center we have a policy of stabilization of high-risk patients in so far as is possible prior to primary surgical intervention in all patients. The objective of this study was to compare the outcome in our high-risk versus low-risk infants with coarctation, to determine what the actual difference in morbidity, mortality, and recurrence rates are, and to compare this with the primary angioplasty studies for coarctation published over the last ten years. The study looked at all infants in Ireland who had coarctation repair over 20 years, and followed over 24 years.
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Material and Methods
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Approval for the study was granted from the Institutional Ethics Committee and the need for individual consent was waived. A total of 215 infants had coarctation repair in Ireland from 1986 to 2005. One hundred ninety-two had complete follow-up to January 2009 and were used for the study. Of the 23 patients who were not included there were 2 mortalities. A detailed retrospective chart review was undertaken to create a database in line with institutional guidelines. All infants in the country were treated in the single unit with standardized preoperative and postoperative care, with all coarctation repairs performed by one of three surgeons over the period. For the study, high-risk patients were defined as those requiring either an epinephrine infusion for at least 24 hours preoperatively to optimize cardiac output, or mechanical ventilation and milrinone infusion for at least 24 hours preoperatively for cardiorespiratory distress. All of the high-risk patients required prostaglandin infusion for a duct-dependent coarctation to optimize the patient for at least 24 hours prior to surgery. All high-risk patients had a period of ventricular dysfunction prior to surgery. According to this definition, 56 infants (29%) were high risk.
Surgical Techniques
All patients underwent surgical repair through a left posterolateral thoracotomy. Extended end-to-end anastomosis was performed in the majority of cases as described previously by our group [4]. Subclavian flap anastomosis was performed in a small number of patients in the 1980s, but this was supplanted by the extended end-to-end anastomosis. A pulmonary artery band was placed during the same procedure in those with an unrestrictive ventricular septal defect.
Follow-Up
Patients were followed up in the cardiology clinic at 6 weeks, 3 months, 6 months, yearly, and then every 2 to 3 years as dictated by their clinical condition. Right arm-left leg blood pressure gradients were measured at discharge and at each cardiology visit. Doppler transthoracic echocardiography was performed at discharge and intermittently at follow-up visits as clinically required.
Statistical Analysis
Mortality rates refer to in-hospital mortality after coarctation surgery. A morbidity was postoperative seizures (1%), cerebral infarction (0.5%), reexploration (2.1%), and temporary recurrent laryngeal nerve palsy (0.5%). Morbidity rates were calculated by summing the number of these events for each group. All results are reported as mean ± standard error of the mean (SEM). Differences in variables such as age and weight were calculated using analysis of variance with Bonferroni comparison of means. The 2 x 2 
2 tests for comparison of incidences with subsequent Fisher exact test. A p value less than 0.05 was considered significant.
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Results
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As expected, the high-risk patients were significantly younger at 18 ± 4 days, and had a lower weight at 3.3 ± 0.1 kg, compared with the low-risk patients (Table 1). This is due to the fact that they were more likely to have duct-dependent lesions and present in shock or multiorgan failure as a consequence of duct closure. In both groups there was a male predominance. There was an equal distribution of comorbid cardiac lesions between both groups (Table 2). Also, both groups had more than 10% of patients with either single ventricle, transposition, unbalanced atrioventricular canal, or double outlet right ventricle, a challenging group to treat with isolated coarctation repair. Despite these factors, the cross-clamp times were acceptable (around 18 minutes in both groups) (Table 3), and the smaller, younger high-risk patients did not have longer cross-clamp times than the low-risk patients. The high-risk patients were also disadvantaged by the fact that significantly more required a concomitant pulmonary artery band at the same procedure (Table 3). Despite this there was no significant difference in postoperative morbidity, which was low at 3% to 7% (p = 0.11).
There was a trend toward higher mortality in the high-risk group (7% vs 2% in the low-risk patients, p = 0.07), with 2 of the 4 mortalities in infants with reduced function who fibrillated during aortic cross-clamp. There was also a higher incidence of a gradient greater than 15 mm Hg at discharge (Table 4), but these patients had no evidence of organ compromise. On follow-up there was a trend toward more reintervention for recurrent coarctation in the high-risk group, but this was low at 11% of patients over the 24-year period of follow-up (Table 4). However, two thirds of these patients were easily treated with a single episode of balloon angioplasty, at a mean of 3.8 ± 2.2 years later.
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Comment
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In our patient group, the low-risk infants have an excellent outcome with primary surgical repair of coarctation. Only 4% of these patients required reintervention for recurrent coarctation over the 24-year follow-up period, with a low morbidity rate of 3% and an in-hospital mortality rate of 2%. This included patients who had subclavian flap repair in the 1980s. We have also previously published our results from a single surgeon (A.E.W.) using solely the extended end-to-end anastomosis technique, with a mortality rate as low as 0.5% and recurrence rate of 2.2% [4]. Other groups have, similarly, recently reported low mortality rates of 0.6% to 2.4%, and recurrence rates of 6% to 11% [5, 6]. Again, in the cases of recurrent coarctation, a single episode of balloon angioplasty is successful in treating the majority of restenosis in these studies. While many surgeons now believe that extended end-to-end anastomosis is the optimal repair technique, groups that have used exclusively the subclavian flap technique have also shown good results. The Johns Hopkins group in Baltimore [7] has a 4% mortality rate and an 11% reintervention rate, with three quarters managed with angioplasty. Long segments of hypoplastic arch can also be repaired without the need for cardiopulmonary bypass using the reverse subclavian flap technique in combination with extended end-to-end anastomosis [8]. With these low mortality rates and low recurrence rates, primary surgical repair is generally the preferred option for low-risk infants.
The majority of high-risk patients will be the younger neonates who have presented with ventricular dysfunction in a shocked state, or with multiple organ dysfunction due to poor distal perfusion, both as a consequence of excessive afterload from a tight coarctation and duct closure. These infants are treated with prostaglandin infusions, inotropes, and ventilation to optimize their systemic perfusion, and allow for some recovery of ventricular function. The majority of infants will show some improvement, particularly if the duct reopens. However, their ventricular function may still be suboptimal at the time of surgery for their coarctation. In recent years it has been suggested by some groups that perhaps a policy of angioplasty initially to allow for more of a recovery, and then delayed definitive intervention when the coarctation reoccurs might be a better approach. While this sounds logical, there are a few concerns with this. First, any significant residual gradient postangioplasty still places an afterload challenge on the heart, which may not allow for complete recovery of ventricular function. This is particularly the case in neonatal coarctation, as the incidence of distal arch hypoplasia in association with coarctation can be as high as 50% to 80% [9], and angioplasty fails to deal with this. Second, waiting until the coarctation reoccurs means that the heart is exposed to this afterload challenge for a longer period than if primary surgical repair was performed initially. Third, one is assuming that balloon angioplasty in high-risk infants carries minimal risk, or at least significantly less risk than primary surgical correction. On reviewing the literature we have not come across any other study which specifically looked at outcome from primary surgical repair in high-risk patients, to allow us to compare with angioplasty. In our patient group, once the patient was optimized in as far as was possible, then surgery was undertaken, even if there was still significant ventricular dysfunction or organ dysfunction. As expected the high-risk infants were smaller and younger and 25% of them required a pulmonary artery band, which was significantly more than the 15% in our low-risk infants. Despite this the cross-clamp times were the same as our low-risk group, and extended end-to-end anastomosis could be performed in the majority of infants, with equivalent morbidity to the low-risk group. There was a trend toward higher mortality (7%) as would be expected in these patients with poorer ventricular function and the recurrence rate was higher at 11% versus 4%, but three quarters of the recurrences were easily treated with angioplasty.
In order to compare these results with balloon angioplasty, we performed a PubMed search for all balloon angioplasty studies in infants with coarctation, where angioplasty was the initial treatment, published over the last 10 years. We found eight studies that fulfilled these criteria and summarized the data in table form (Table 5). Only two of the studies actually looked at high-risk infants. Of the other six studies were the following: two excluded infants with hypoplasia of the transverse arch [3, 10]; in one, none of the infants required prostaglandins prior to intervention [11]; one excluded infants less than 2 months old [12]; one excluded all patients with complex cardiac anatomy, which was 52% of the neonates presenting with coarctation, and infants with hypoplasia of the distal arch or isthmus were not offered angioplasty and instead assigned to the surgery group [13]. These studies represented low-risk infants and although there were no initial mortalities in any of these studies, the reintervention rate was between 14% and 83% depending on how long the infants were followed up. Also, no mention was given of morbidity or mortality as a result of recurrent coarctation and repeated intervention. In the two high-risk studies, the mortality rates were 17% and 21%, significantly higher than the 7% seen in our high-risk surgically treated infants. In the study with the 21% mortality [2], all deaths occurred during the angioplasty procedure, and in the study with 17% mortality [1], one third of the deaths occurred during angioplasty. In both studies the reintervention rate for recurrent coarctation was high; 73% within 10 days in one study [2] and 77% by 12 years in the other study [1]. Again both significantly higher than the 11% during 24 years of follow-up seen in our high-risk surgically treated infants. There were two other concerns with all of the balloon angioplasty studies. In most of the studies there was loss of the femoral pulse at the site of intervention in 12% to 18% of infants (Table 5). Although this tended to recover with treatment with a heparin infusion, one study [3] reported that 16.5% of infants at follow-up angiogram had a chronic femoral artery occlusion. This is of concern, as the long-term sequelae of this are unknown; ie, do they have the potential to develop intermittent claudication in adult life? The second concern is the risk of aneurysm formation at the coarctation site with balloon angioplasty. The mechanism of action with balloon angioplasty in infant coarctation is to create a controlled tear in the intima and partial media to increase the diameter of the vessel, which then heals by fibrous scar tissue. However, there is a limit to how controlled one can be with a balloon in determining the thickness and extent of the tear, which can then lead to aneurysm formation. In the studies we found the risk of aneurysm formation was low, but one study [13] found that in those who required a second episode of angioplasty 38% developed a saccular aneurysm. Stenting an area at the time of angioplasty may reduce the risk of aneurysm formation but unfortunately the current stents do not degrade and can be further dilated with growth of the vessel but to a limited size, particularly if a small stent is inserted first, as would be required for a neonate or infant. It is important to keep in mind that angioplasty and stenting may play a role in the future as primary treatment if biodegradable stents become a reality.
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Table 5 Native Coarctation Angioplasty Studies in Infants Published in the Last 10 Years. Only the Top Two Studies Apply to Infants Who are "High Risk," Comparable With the Infants in Our Study
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The results from this study demonstrate that primary surgical repair of coarctation in high-risk infants is associated with a 7% mortality, low morbidity, and low recurrence rate. When compared with the currently available primary angioplasty studies in high-risk infants, the outcome is significantly better with primary surgical repair. If repeated intervention is required after surgery, balloon angioplasty is definitely the preferred method, as children are usually older, in which femoral artery complications are presumably less. One limitation of our study is that many of our infants made significant improvement in ventricular dysfunction or cardiorespiratory failure prior to surgery, as a result of at least a 24-hour period of stabilization. Therefore, although these patients were "high-risk," many were significantly improved prior to surgery.
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Acknowledgments
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We, the authors had full control of the design of the study, methods used, outcome parameters, analysis of data, and production of the written report.
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References
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Abstract
Introduction
