The optimal age for surgical correction of CAVC defect has been addressed in several studies, most of which showed that successful repair at an early age was associated with competent AV valves at time of diagnosis, even in the presence of a cleft in the LAVV component (18, 19). Patients repaired at older ages were found to be more likely presenting with an incompetent AV valve (19, 20). This may be due to chronically elevated QP/QS playing an important role in the onset of annular dilatation and secondary LAVV incompetence (9, 19). Early correction has been proposed to reduce the incidence of LAVV regurgitation (LAVVR) in the postoperative follow-up period (21, 22). This appears to be the most important factor affecting postoperative morbidity and mortality (10). Avoiding irreversible pulmonary hypertension, which may develop before the age of six months particularly in the presence of Trisomy 21, is another reason to justify earlier repair (10, 21). Some studies advocate that the optimal timing for surgical intervention in patients with CAVC defect is when symptoms of congestive heart failure cannot be managed by medical therapy (23). Others believe that repair at the age of 4 to 6 months, before developing severe pulmonary hypertension, gives better results with no additional morbidities or mortality (21, 22, 24).
In our study, we found no statistically significant difference between early surgical repair of CAVC defect in the first 6 months versus later repair, both regarding mortality and postoperative LAVVR. The only significant finding was in the ICU duration, which was longer in the younger age group. Stellin et al (10) performed a study assessing surgical treatment of CAVC defects in children before 3 months of age, with findings demonstrating that repair of CAVC under 3 months of age is the ideal approach to this malformation with a lower mortality rate at operation compared to older patients (10, 24). Logistic analysis showed that an operative age after 3 months is compared to an age before or equal to 3 months, an incremental risk factor for hospital mortality with an odds ratio of 4.8 (95% confidence limit 1–23.5) (P value = 0.05) (10). In the long term, freedom from reoperation for LAVV incompetence is higher when compared to children repaired at an older age (10).
Parikh et al(25) found no differences between the early (< 90 days) and late repair (> 90 days) age-groups at surgery for the outcomes of postoperative length of stay, heart block requiring pacemaker placement, rate of moderate or greater LAVVR, reoperation for LAVVR, and mortality(25).
Both modified single patch and double patch techniques can be used for the repair of CAVCD, with the former being superior in having shorter bypass time and cross clamp time, making it more popular(11, 26), although some surgeons believe that it may have associations with higher incidence of LVOT obstruction(27).
In our study, when compared to the double patch techniques, patients with a modified single patch had significantly shorter cross clamp time, bypass time and duration of ICU stay. Surgeons’ preference in deciding which technique to use in the surgical repair is one important factor, some surgeons tend to use double patch technique with large VSD component, others favour the use of modified single patch technique in complete AVSD with large VSD (larger than 0.8 mm and up to 1.5 mm), both, however, were found to have comparable results and outcomes(11, 26, 27).
Addition of posterior annuloplasty to the common AV valve repair was suggested to prevent late re-appearance of LAVVR(26). In this study, it showed a protective effect against moderate to severe LAVVR and short term mortality 6 months postoperatively, when compared to closure of cleft only. We believe that posterior annuloplasty maintains the valve competency and also restricts progressive dilatation of the LAVV, hence decreasing the need for reoperation. In a study performed by Myers et al, 219 patients were included to evaluate the impact of annuloplasty at CAVC repair on postoperative LAVV function(28). The cleft was closed completely in 192 patients (88%). 65 patients had annuloplasty (39 commissural, 32 posterior). There were 5 early deaths (2.3%). At discharge, 4 patients (1.9%) had more than mild regurgitation and no patients had significant inflow gradients. During a follow-up of 2.7 ± 2.1 years, there were 6 late deaths (2.8%) and 16 patients (7.3%) required LAVV reoperation. Two of 65 patients (3.1%) with annuloplasty required reoperation, compared to 14 of 148 without annuloplasty (9.5%, p = 0.16). In propensity matched analysis, annuloplasty was significantly protective of ≥ moderate LAVVR (OR 0.19, p = 0.008) and non-significantly of reoperation (OR 0.28, p = 0.099)(28).
There was a significant difference between Trisomy 21 patients and Non-Trisomy 21 patients regarding postoperative, early and 6 months follow-up LAVVR. Additionally, there was a significantly higher incidence of common AVV dysplasia and malformation in Non-Trisomy 21 patients when compared to Trisomy 21 patients. The significant difference between postoperative LAVVR between the two groups may be due to the difference in AV valve dysplasia and malformations, which makes surgical repair of LAVV and maintenance of valve competency much more difficult, regardless of surgical technique used.
Formigari et al. found there were no significant differences in survival between Trisomy 21 and Non-Trisomy 21 patients with overall mortality being 7.7% (29). Survival was 94% among patients with Trisomy 21 versus 86% of Non-Trisomy 21patients (p = 0.12). When comparing incidence of reoperation due to postoperative LAVVR or LVOT obstruction, a higher prevalence of reoperation in CAVC was found in Non-Trisomy 21 patients (81.4% vs 94.6%, p = 0.04), due to the higher prevalence of anomalies of the mitral valve (4.9% vs 1.8%, p 0.03), as well as higher LVOT prevalence (7.3% vs 0%, p 0.01)(29).
Kaza et al found some preoperative and intraoperative differences between the two groups but of no significance, and outcomes were found to be similar(30). Hospital courses were also similar with the exception of a number of in-hospital complications (higher in the Non-Trisomy 21 group). Mortality at 6 months was identical at 4%, but there was a trend towards more reoperations in the first 6 months in the Non-Trisomy 21 group (13% vs. 2%, p = 0.06)(30). Moderate or severe LAVVR was more likely in the Non-Trisomy 21 group prior to AVSD surgery, however, the prevalence of LAVVR did not differ at 1 month and 6 months post-surgery(30).
We can conclude that Trisomy 21 is no longer a risk factor for adverse outcomes regarding postoperative LAVVR and mortality, so early intervention in the first 6 months in patients with Trisomy 21 is advocated to provide better results when compared to Non-Trisomy 21 patients, and gives comparable results compared to delaying surgery after 6 months.
In this study, we ensured that our methodology was coherent. We optimised our selection criteria to make our findings generalisable to a wider patient population. However, this study still has a number of limitations, namely a limited study sample and a short follow-up. Other limitations, owing to the retrospective nature of the study, included possible unaccounted confounders such as sex, ethnicity and the presence of comorbidities, heterogeneity of operations as well as information bias during data collection.