Atrioventricular septal defects are one of the congenital heart defects for which outcomes are used to assess the pediatric heart surgeon’s skill as well as institutional expertise [3
]. This multicenter observational study reports contemporary outcomes for all AVSD subtypes and analyzes patient characteristics, resource utilization, and practice variation as potential predictors of these outcomes.
After adjusting for subtype, centers were similar in age at repair and days of ventilation, intensive care, and hospitalization. The outcomes at 6 months compared favorably with those reported from single-center studies. Specifically, overall mortality was low, with only 6 deaths (3%) compared with the 7% to 15% mortality rate reported from other centers [9
]. Septal defects (> 3 mm) occurred in 2% at the 6-month follow-up, similar to previous reports where residual defects occurred in 5% or fewer [12
]. Subaortic stenosis and LAVV stenosis were uncommon and lower than the 5% previously reported for these lesions [14
], but this low prevalence may be attributed to the short duration of follow-up.
Residual LAVVR remains the Achilles’ heel of AVSD repair, with 3% (7 of 215) requiring reoperation and 26% with moderate or severe LAVVR by the 6-month follow-up. AVSD subtype and center were not independent predictors of the prevalence of moderate or severe LAVVR at 6 months. Despite the nearly uniform adoption of complete LAVV cleft closure, the prevalence of significant LAVVR has remained unchanged during the past decade [9
]. To decrease LAVVR, some surgeons have advocated the addition of an annuloplasty [16
], but this remains controversial and its use varied widely among the 7 centers. For all subtypes, some surgeons performed annuloplasty prophylactically, even in those with mild or no preoperative LAVVR, some used it only if the preoperative LAVVR was graded as moderate or severe, and others did not use it at all. Regardless of the reason for its use, however, we were unable to demonstrate that annuloplasty decreased the prevalence of moderate or severe LAVVR at 6 months postoperatively. In fact, for reasons that are unclear, annuloplasty appeared to have some negative aspects in this study, where its use was associated with poorer weight gain in TAVSD patients and increased resource utilization in the CAVSD group.
Older log(age) at repair and the presence of moderate or severe LAVVR within 1 month of the operation predicted moderate or severe LAVVR at the 6-month follow-up. The prevalence of moderate or severe LAVV regurgitation clearly peaked after later operations for PAVSD but increased linearly for TAVSD/CAVSD. Other investigators have noted this trend and advocated earlier repair [9
]. Despite earlier repair during the past decade, however, the prevalence of postoperative LAVVR has remained unchanged [9
]. Our data do not permit us to determine the ideal time of repair to minimize postoperative LAVVR.
Patient characteristics differed by subtype. CAVSD and canal-type VSD had a significantly more patients with trisomy 21, more associated cardiac defects, and longer cardiopulmonary bypass and cross-clamp times compared with PAVSD or TAVSD. We confirmed the commonly held belief that CAVSDs were more likely to have lower weight-for-age z scores at the time of repair. More surprising is the finding that weight gain significantly improved 6 months after repair in all subtypes, including those with PAVSD, and that all subtypes showed a similar increase in weight-for-age z scores. Although the predictors of improvement in weight varied with subtype, all subtypes likely share the common characteristic of being more nutritionally depleted before the operation and thus are able to display better catch-up growth after repair.
This study has several limitations: First, the small numbers of each subtype limited the ability to detect some associations and interactions of outcome predictors and subtype.
Second, because our data were collected both prospectively and retrospectively, all measurements could not be centrally interpreted, and 6-month postoperative echocardiographic data were not available for some participants. In addition, reliable and validated echocardiographic methods for quantitative evaluation of LAVVR grade are not available for children, particularly in the setting of multiple or eccentric jets characteristic of the repaired AVSD valve. We used qualitative assessment of the color Doppler jet because this was the standard for clinical decision making in all 7 centers. This has also been the most commonly used method for grading LAVVR in other AVSD studies, allowing for comparisons to be made.
Finally, we were unable to explore the effect of variations in annuloplasty technique on valve function because annuloplasty details were not uniformly available from the operative reports.
In conclusion, survival in the current era is excellent, with few residual defects after surgical repair for all AVSD subtypes at a similar age of repair among the 7 centers. After accounting for age at repair, we found subtype and center were not important prognostic indicators of resource utilization, postoperative LAVVR, or improvement in growth. Significant postoperative LAVVR is the most common sequela, with a similar prevalence across the centers at 6 months. Annuloplasty use varied among centers and failed to decrease the prevalence of moderate or severe LAVVR at the 6-month follow-up in this cohort. Older age at repair was an independent predictor of moderate or severe LAVVR. Further investigation is needed to determine if intervening in center practice variation or earlier referral of subtypes traditionally repaired at an older age can affect the relatively high prevalence of postoperative LAVVR.