Discussion

Late presentation of CHD remains an important reality in low- and middle-income countries. Unlike high-income settings, where most patients with tetralogy of Fallot undergo complete repair during infancy, delayed diagnosis, referral pathways, financial constraints, geographical barriers, and limited availability of specialist services continue to postpone definitive treatment. ^{Reference Das, Dutta, Das, Ghosh and Chowdhuri6} Cheng et al., in a systematic review of 67 studies, identified delayed diagnosis, financial limitations, difficulty reaching treatment centres, and inadequate caregiver education among the major pre-operative barriers, together with limitations in specialised workforce and surgical resources. ^{Reference Cheng, Heo, Joos, Vervoort and Joharifard7} Thus, late-presenting tetralogy of Fallot in India should not simply be regarded as an unusual manifestation of the natural history of the disease but also as a reflection of continuing disparities in access to congenital cardiac care.

Importantly, increasing age at repair does not necessarily translate into prohibitive operative risk. Earlier Indian experience has demonstrated that despite these challenges, complete repair can provide meaningful long-term survival and functional improvement. In a large series of 284 patients aged 14–50 years, Bisoi et al. reported that 94% of survivors were in NYHA functional class I, with 10-year freedom from reoperation exceeding 90%. ^{Reference Bisoi, Murala and Airan4} The International Quality Improvement Collaborative (IQIC) analysed 2,164 tetralogy of Fallot operations from 32 centres in 20 low- and middle-income countries. More than half (54%) of primary repairs were performed beyond 1 year of age, 755 (34.9%) of them being in the age range of 2 to 27 years. In this study, older age was not independently associated with mortality. ^{Reference Sandoval, Carreño and Novick8} Our results extend this observation into a substantially older population. The mortality of 1.06% in the present cohort compares favourably with previously reported adult series. Bhushan et al. reported 2% early mortality among 45 patients with a median age of 21 years, while Erdoğan et al. reported 3.1% hospital mortality among 64 patients aged ≥ 14 years. ^{Reference Bhushan, Chugh and Loona3,Reference Erdoğan, Bozbuğa and Kayalar9} Even patients presenting considerably later can undergo successful correction. Talwar et al. reported acceptable outcomes in 41 patients aged 30–52 years, with two early deaths. ^{Reference Talwar, Meena and Choudhary10} At extremes, the oldest reported cases of tetralogy of Fallot undergoing surgical repair or correction for the first time at an advanced age involve patients in their 78th and 83rd years of life. ^{Reference Katayama, Isobe, Ozawa and Fujii11}

Our study demonstrates that primary complete repair of tetralogy of Fallot in late-presenting adolescents and adults can be performed with low early mortality and acceptable perioperative morbidity. In this cohort of 94 patients aged ≥ 13 years, the median age was 15 years, and despite the prolonged period of exposure to cyanosis and right ventricular pressure overload, 30-day mortality was only 1.06%. Post-operative recovery was also relatively rapid, with a mean ventilation duration of 7.7 ± 7.1 hours, ICU stay of 3.9 ± 1 days, and post-operative hospital stay of 4.6 ± 1.3 days. Early reintervention was required in only two patients during a mean follow-up of 38.4 months. These findings reinforce the concept that chronological age alone should not preclude definitive repair in appropriately selected patients presenting late (Figure 1).

Figure 1.

Surgical and clinical outcomes after late TOF repair. TOF = tetralogy of Fallot.

Late presenters nevertheless represent a physiologically distinct population. Long-standing cyanosis may result in secondary erythrocytosis and coagulation abnormalities, while chronic right ventricle pressure overload produces substantial hypertrophy and may eventually impair ventricular function. Aortopulmonary collaterals are another important feature. The contemporary review of late-presenting CHD emphasises the need to evaluate polycythaemia, coagulation abnormalities, brain abscesses, and aortopulmonary collaterals specifically in late tetralogy of Fallot. ^{Reference Das, Dutta, Das, Ghosh and Chowdhuri6,Reference Khan, Tufail, Afridi, Iqbal, Khan and Waheed12,Reference Khajali, Mohammadi and Toloueitabar13} Surgical repair of tetralogy of Fallot can be performed in both adult and paediatric populations with acceptable outcomes. Khan et al. showed that the mortality rate was found to be slightly greater in the paediatric population compared to the adults. However, it can be seen that the number of post-operative complications is greater in adults. ^{Reference Khan, Tufail, Afridi, Iqbal, Khan and Waheed12} In our series, 11 patients underwent pre-operative coil embolisation of significant aortopulmonary collaterals. This strategy is supported by the experience of Talwar et al., in which 28 of 41 (68.2%) patients had significant collaterals that were occluded before repair. Their study further demonstrated that lower pre-operative oxygen saturation correlated with greater inotropic requirements and longer ventilation, ICU, and hospital stay, while aortopulmonary collaterals, high haematocrit, and right ventricle dysfunction were associated with greater post-operative support. ^{Reference Talwar, Meena and Choudhary10} Khan et al. reported a 30-day mortality of 8% in a series of 80 adult tetralogy patients from Pakistan. ^{Reference Khan, Tufail, Afridi, Iqbal, Khan and Waheed12} Khajali et al. from Iran reported an in-hospital mortality of 5.1% in a series of 94 adult tetralogy repair. ^{Reference Khajali, Mohammadi and Toloueitabar13} These observations underline the importance of meticulous pre-operative optimisation rather than considering late repair itself inherently high risk.

The surgical strategy for the right ventricular outflow tract is particularly relevant in this population. In the present series, 69 patients underwent transannular patch repair and 25 underwent a pulmonary valve-preserving strategy. Despite the different right ventricular outflow tract approaches, there were no significant differences in ventilation duration, ICU stay, or post-operative hospital stay between the groups (Table 3). This suggests that, at least with respect to early post-operative recovery, an appropriately selected transannular patch does not impose an additional immediate penalty in late presenters (Figure 2). Historical adult series similarly demonstrate frequent use of transannular patch; Erdoğan et al. required transannular reconstruction in 68.7% of patients, similar to our cohort. ^{Reference Erdoğan, Bozbuğa and Kayalar9}

Figure 2.

Early post-operative outcomes by RVOT repair strategy. RVOT = right ventricular outflow tract.

However, equivalence in early outcomes should not be interpreted as equivalence in long-term consequences. Chronic pulmonary regurgitation following transannular patch may lead to progressive right ventricle dilatation, ventricular dysfunction, arrhythmia, and eventual pulmonary valve replacement in few patients in their follow-up of 62.3 months. ^{Reference Erdoğan, Bozbuğa and Kayalar9} This emphasises continued echocardiographic surveillance, particularly for right ventricle dilatation, arrhythmias, residual right ventricular outflow tract obstruction, and significant pulmonary or tricuspid regurgitation. In an earlier report from Brazil, Atik et al. reported an early mortality of 5.1% and late mortality of 7.7% over a mean follow-up of 45.1 months. ^{Reference Atik, Atik and da Cunha14} Ducas et al. analysed 230 adults with repaired tetralogy of Fallot and showed that the need for pulmonary valve replacement was six times higher patients with transannular patch over a median follow-up duration of 7.9 years. ^{Reference Ducas, Harris and Labos15} Contemporary literature therefore increasingly favours preservation of the pulmonary annulus and valve whenever this can be achieved without leaving clinically important right ventricular outflow tract obstruction. Various strategies including intraoperative balloon pulmonary valvuloplasty, pulmonary valve reconstruction, and commissurotomy have been described during the surgical procedure based on the developmental status and anatomical characteristics of the right right ventricular outflow tract, pulmonary valve, and pulmonary artery. ^{Reference Yi, Wang and Xu16} However, it remains clear that optimal outcome after surgical correction of tetralogy of Fallot depends adequate relief of right ventricular outflow tract obstruction and secure closure of the ventricular septal defect. Kaushal et al. demonstrated the importance of distinguishing between dynamic gradients after repair from important mechanical obstruction as a strategy for revision due high post-operative right ventricle–pulmonary artery gradient. ^{Reference Kaushal, Radhakrishanan and Dagar17}

Our finding of comparable early outcomes between transannular patch and valve-preserving repair is reassuring but cannot address this important long-term trade-off. We do not prefer primary implantation of pulmonary valve during routine tetralogy repair in adolescents and adults in tetralogy of Fallot –pulmonary subset to avoid reoperation due to prosthesis degeneration in future. Although there are reports in literature about good results with primary pulmonary valve replacement during tetralogy of Fallot repair in adults, routine pulmonary valve replacement during primary tetralogy of Fallot repair in adults is not standard practice. ^{Reference Liu, Liu and Zaki18,Reference Jain, Rajan and Patel19} We reserve this strategy in selected cases to manage severe right ventricular volume overload and reduce long-term morbidity.

Longer follow-up incorporating right ventricle dimensions and function, pulmonary regurgitant fraction, exercise capacity, rhythm disturbances, and freedom from pulmonary valve replacement will be necessary to determine whether valve preservation confers a meaningful late advantage in this specific population.

Branch pulmonary artery intervention at primary surgery was required in 16 patients in our cohort, while only 2 patients subsequently required early reintervention, both for left pulmonary artery stenosis requiring stenting. The low early reintervention rate is encouraging. Nevertheless, late tetralogy of Fallot repair should be regarded as the beginning of lifelong congenital cardiac surveillance rather than a definitive endpoint. Historical data demonstrate excellent functional improvement following adult repair, but residual right ventricular outflow tract lesions, pulmonary regurgitation and arrhythmias remain important late concerns. In the Erdoğan series, 16-year actuarial survival was 89.2% ± 4.9%, with 6.2% requiring reoperation. ^{Reference Erdoğan, Bozbuğa and Kayalar9} This distinction between excellent early surgical rescue and the continuing burden of repaired tetralogy of Fallot is particularly relevant when counselling late presenters.

The favourable outcomes in this study also have implications beyond operative technique. Late presentation is ultimately a marker of gaps in access to congenital cardiac care. The systematic review by Cheng et al. highlights that barriers continue even after surgery through inadequate counselling, fragmented follow-up, and shortages of critical-care and adult congenital services. ^{Reference Das, Dutta, Das, Ghosh and Chowdhuri6} Therefore, demonstrating that late repair can be performed safely should not normalise delayed treatment. Complete repair in infancy remains the preferred strategy. ^{Reference Hribernik, Boardman and Crossland2} Rather, these results provide reassurance that adolescents and adults who have missed the optimal window should not be denied definitive treatment solely because of age.

Nevertheless, the present experience supports a pragmatic message relevant to contemporary congenital cardiac practice in low- and middle-income countries: with careful anatomical assessment, management of aortopulmonary collaterals, appropriate right ventricular outflow tract strategy, and meticulous perioperative care, primary repair of late-presenting tetralogy of Fallot can achieve reasonable early outcomes. This is consistent with contemporary evidence that appropriately selected and managed late-presenting CHD can be treated with acceptable results despite delayed presentation.