Editorial Comment: Preserving the Pulmonary Valve in Tetralogy of Fallot: Toward Better Long-Term Outcomes

Abstract

Tetralogy of Fallot (TOF) has undergone a remarkable transformation from a congenital heart defect in which operative survival was once the principal concern to a condition in which most successfully repaired children can now be expected to survive well into adulthood. As survival has improved, the goals of surgical repair have correspondingly evolved. Contemporary management must consider not only successful relief of right ventricular outflow tract (RVOT) obstruction but also the quality and durability of the circulation created for the patient's lifetime. In this context, preservation of pulmonary valve function has emerged as an increasingly important component of TOF repair because chronic pulmonary regurgitation can adversely affect right ventricular size and function, exercise capacity, arrhythmia risk, and the subsequent need for pulmonary valve replacement [1-3]. The study by Ullah et al. provides timely prospective evidence addressing this important surgical question in a Pakistani pediatric population [1]. The authors compared three approaches to pulmonary valve and RVOT management—pulmonary valve preservation, monocusp reconstruction, and right atrial appendage (RAA) reconstruction—in 150 children undergoing complete TOF repair. Importantly, this was a prospective but non-randomized comparative cohort study in which the surgical strategy was selected according to pulmonary annulus size, valve morphology, severity of RVOT obstruction, and intraoperative anatomical findings [1]. This approach reflects real-world congenital cardiac surgical practice, where anatomy often determines what can safely and effectively be preserved. The principal findings favor pulmonary valve preservation in anatomically suitable patients. Children undergoing valve-preserving repair had shorter operative, cardiopulmonary bypass, and aortic cross-clamp times, as well as shorter durations of mechanical ventilation, intensive care unit (ICU) stay, and hospitalization [1]. Equally important, the benefits were accompanied by favorable early echocardiographic findings, including higher tricuspid annular plane systolic excursion (TAPSE), lower postoperative RVOT gradients, higher left ventricular ejection fraction, and less severe pulmonary insufficiency [1]. The pulmonary insufficiency findings are particularly relevant. Mild pulmonary insufficiency was observed in 50% of children undergoing pulmonary valve preservation, compared with 36% after RAA reconstruction and 20% after monocusp reconstruction, whereas severe pulmonary insufficiency occurred in 16%, 22%, and 28%, respectively [1]. TAPSE was also highest after valve preservation, reaching 16.0 ± 1.8 mm [1]. These findings provide an important physiological message: when adequate relief of RVOT obstruction can be achieved without sacrificing the native pulmonary valve, preserving valve competence may contribute to more favorable early right ventricular haemodynamics. The clinical differences were also meaningful. Compared with monocusp reconstruction, pulmonary valve preservation was associated with approximately 1.7 fewer days in the ICU and 2.7 fewer days in hospital. TAPSE was approximately 2 mm higher, while the postoperative RVOT gradient was approximately 11 mmHg lower [1]. Furthermore, after adjustment for age, sex, body weight, pulmonary annulus Z-score, previous Blalock–Taussig shunt, and preoperative RVOT gradient, pulmonary valve preservation remained independently associated with shorter ICU and hospital stays, higher TAPSE, lower postoperative RVOT gradients, and a lower likelihood of reintervention within 30 days [1]. These observations are consistent with the broader direction of contemporary evidence. Systematic reviews and meta-analyses comparing valve-sparing repair with transannular patch approaches have reported less pulmonary regurgitation and favorable perioperative outcomes, including reductions in cardiopulmonary bypass time, ventilation duration, ICU stay, and hospital stay [4-6]. Long-term observational studies have similarly strengthened interest in preserving native pulmonary valve function whenever anatomically feasible [4,7]. The present study therefore contributes valuable prospective evidence from South Asia to an increasingly important area of congenital cardiac surgery. The rationale for pulmonary valve preservation extends well beyond the immediate postoperative period. Chronic pulmonary regurgitation after TOF repair can lead to progressive right ventricular volume overload, dilatation and dysfunction, reduced exercise capacity, ventricular arrhythmias, and eventual pulmonary valve replacement [2,3,7]. Consequently, the objective of contemporary TOF surgery should not simply be to create an unobstructed RVOT. The more sophisticated objective is to achieve adequate relief of obstruction while maintaining the most favorable possible relationship between RV pressure, pulmonary valve competence, and long-term right ventricular function. However, the findings of Ullah et al. must be interpreted within an important methodological context. Treatment allocation was not randomized. Children underwent pulmonary valve preservation precisely because their pulmonary valve and RVOT anatomy permitted this approach [1]. It is therefore possible that these patients had inherently more favorable anatomy than those requiring monocusp or RAA reconstruction. Although multivariable analysis accounted for several important baseline factors, detailed leaflet morphology, annular compliance, branch pulmonary artery anatomy, and RVOT morphology were not systematically incorporated into the adjusted models [1]. This issue of confounding by indication is central to interpreting the study. The findings demonstrate that pulmonary valve preservation was associated with better early outcomes; they do not establish that the surgical technique itself caused those outcomes. For example, shorter operative and bypass times may partly reflect less complex underlying RVOT anatomy rather than an intrinsic advantage of valve preservation. This distinction is especially important when translating observational evidence into surgical recommendations. Patient selection is therefore critical. Previous studies have demonstrated that pulmonary valve morphology, annular dimensions, leaflet characteristics, and the degree of residual RVOT obstruction influence both the feasibility and durability of valve-sparing repair [4,8]. Pulmonary annulus size should consequently be considered as part of a broader anatomical assessment rather than as the sole determinant of whether the native valve can be preserved. The surgical objective should remain individualized: preserve the pulmonary valve where feasible, but not at the expense of clinically important residual RVOT obstruction. Monocusp reconstruction likewise retains an important role. When transannular enlargement is unavoidable, creation of a monocusp valve may reduce early pulmonary regurgitation and provide a degree of pulmonary competence during the postoperative period [9,10]. Nevertheless, the available evidence has not consistently demonstrated improvement in harder outcomes such as operative mortality or long-term freedom from reintervention [9]. Thus, improvement in early pulmonary valve physiology should not automatically be equated with durable long-term clinical benefit. This distinction is also evident in the present study. Junctional rhythm, reintubation, sepsis, acute kidney injury, mortality, readmission, reintervention, persistent arrhythmia, and right ventricular failure were numerically more frequent in the monocusp group, but most of these differences were not statistically significant [1]. With only 50 patients in each group and relatively few adverse events, the study had limited statistical power for uncommon clinical outcomes. Absence of statistical significance in this setting should therefore not be interpreted as evidence that the techniques are clinically equivalent. Perhaps the most important limitation is the 30-day follow-up period [1]. The principal theoretical advantage of pulmonary valve preservation is not merely faster recovery from the initial operation, but preservation of right ventricular structure and function over years or decades. The decisive outcomes are therefore long-term pulmonary regurgitation, right ventricular dilatation and remodeling, exercise capacity, arrhythmia burden, freedom from reintervention and pulmonary valve replacement, quality of life, and ultimately survival [2,3,7,11,12]. These outcomes cannot be established from the current study. This limitation should not diminish the value of the reported early findings; rather, it defines the next research question. TOF should now be regarded as a lifelong cardiovascular condition requiring structured surveillance after successful childhood repair [3,11]. Serial echocardiography, cardiac magnetic resonance imaging where available, exercise assessment, rhythm surveillance, and evaluation of right ventricular volumes and function are increasingly important in determining the long-term consequences of the initial surgical strategy [2,3,11,12]. The findings also carry particular significance for Pakistan and other low- and middle-income countries. Congenital cardiac services in resource-constrained settings must manage not only the initial burden of surgical repair but also the long-term consequences of surviving congenital heart disease. A repair that reduces ICU and hospital utilization offers an immediate health-system advantage. More importantly, a durable repair that reduces future reinterventions could potentially decrease the lifelong clinical and economic burden on patients, families, and healthcare systems. Whether pulmonary valve preservation achieves this longer-term benefit in the Pakistani population now warrants prospective evaluation. The study therefore creates an important opportunity for multicentre congenital cardiac res