Choosing the right time for systemic atrioventricular valvular surgery in ccTGA

The classic course of congenitally corrected transposition of the great arteries (ccTGA) usually results in the development of systemic atrioventricular valve (SAVV) insufficiency, whose presence implies a worse prognosis (1). The mechanism may be organic, due to associated structural alterations of the valve; or functional, due to dilatation and remodelling of the right ventricle in the systemic position, in many cases associating ventricular dysfunction. SAVV surgery is hypothesized to interrupt the reciprocal deterioration of SAAV and systemic right ventricle (sRV), mutually exacerbating each other. The great clinical difficulty lies in deciding when to perform surgery.

This article presents a historical cohort from a high-volume centre for SAVV surgery (Mayo Clinic from 1979 to 2022), with analysis of mid- and long-term outcomes, as well as analysis of risk factors and optimal timing of intervention.

108 patients were included, representing the largest series to date. The median age was around 40 years with 16.6% over 60 years. 76% of patients had an intrinsic valve impairment. Median preoperative systemic ventricular ejection fraction (SVEF) was 39%. All but one patient underwent valve replacement, in most cases with a mechanical valve (84%), usually bidisc and  62% of patients received another concomitant procedure. Median follow-up was 12.5 years.

The most noteworthy aspects of the results are:

• The results are good both in the short and long term. The reported early mortality is low (0.9%), as well as the morbidity, even though half of the cohort is referred with a SVEF below 40%.
• Most valvular replacements utilized mechanical valves, and an attempt to repair was unsuccessful in one patient, consistent with historically poor outcomes associated with valve repair (2). Mechanical prostheses were linked to a significantly lower risk of reoperation compared to biologic prostheses - the freedom from reoperation at 10 and 20 years was 100% and 93% for mechanical prostheses, respectively, in contrast to 56.6% and 15.7% for bioprostheses - while no difference in patient survival was observed.
• Two independent predictors of poor late survival were identified: older age at the time of operation and a diminished preoperative SVEF. There is excellent freedom from death, transplantation, or ventricular assist device (VAD) implantation in individuals with higher SVEF, with a 10-year survival rate of 89% if SVEF is greater than 40%. Conversely, significantly poorer outcomes were observed in patients with SVEF less than 32%, resulting in a 10-year survival rate of 57%. Other factors were not related to bad prognosis and consequently associated lesions, the severity of functional class decline, or the risk of repeated sternotomy should not deter the referral for valve operation.
• Finally, independent predictors of postoperative late decline of SVEF identified included preoperative SVEF, associated lesions (VSD or mid-left ventricular outflow tract obstruction), severe SAVV regurgitation, and preoperative creatinine. Notably, a progressive decline in ventricular function was observed in patients with preoperative systemic right ventricular (RV) dysfunction compared to those with a preoperative ejection fraction exceeding 40%, highlighting the importance of early valve intervention.

In summary, this article presents excellent outcomes of SAVV surgery conducted in a specialized center for congenital heart disease. It underscores the importance of early intervention before ventricular function declines, emphasizing that this applies even to individuals with more intricate anatomy or advanced heart failure. Timely SAVV surgery has the potential to mitigate the anticipated long-term attrition of the systemic right ventricle in ccTGA, leading to an improvement in functional capacity (3). However, for patients with severe ventricular dysfunction, transplantation should be considered as a viable alternative.