Author + information
- Division of Pediatric Cardiology and Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
- ↵∗Address for correspondence:
Dr. Frank Cetta, Gonda 6335, Division of Pediatric Cardiology, Mayo Clinic, 200 First Street, SW, Rochester, Minnesota 55905.
Patients with Fontan circulation face an unexpected burden of valve disease that will affect their long-term outcomes. Proper patient selection and execution of an excellent technical operation are essential to Fontan success. However, atrioventricular valve (AVV) competency may be the most important factor to determine long-term quality of life and survival. The question remains whether AVV regurgitation warrants intervention and at what stage.
In this issue of the Journal, King et al. (1) described their experience with AVV issues in a large cohort of patients after the Fontan procedure. They found that by age 30 years, one-third of patients had experienced AVV failure. Unfortunately, AVV failure frequently occurred in childhood (median age: 8.6 years). The cumulative incidence of AVV intervention at 5, 10, and 20 years of age was 6%, 9%, and 11%, respectively.
A successful long-term outcome after Fontan operation is dependent on myriad pre-operative, operative, and post-operative factors that have been identified during the past 4 decades (2). Normal ventricular systolic function and diastolic performance (low-filling pressure, high compliance) are essential pre-operative conditions. The Fontan operation does not improve ejection fraction. Poor pre-operative systolic function is a harbinger of post-operative deterioration. Pulmonary artery size matters; small is bad. Low pulmonary artery pressure and resistance facilitate antegrade pulmonary flow. As identified by Choussat and Fontan in 1977 (3), having more than mild AVV regurgitation is an important predictor of suboptimal outcome. In the current era, when patients with hypoplastic left heart syndrome constitute a larger proportion of patients undergoing the Fontan operation, the durability of a morphologic tricuspid valve in the systemic circulation is largely unknown. In this subset of patients, the importance of flow obstruction in the Fontan circuit plays an important role and is linked to ventricular systolic and diastolic dysfunction. Lastly, but certainly of high importance, maintaining sinus rhythm is essential; loss of atrioventricular synchrony bodes poorly for these patients. Late sudden death from arrhythmias has been linked to the need for AVV replacement during the Fontan procedure (4).
King et al. (1) identified that in those patients with AVV failure, freedom from Fontan failure was 77% at 10-year follow-up and only 54% at 20-year follow-up. This was compared to patients with a “good” AVV who had a 94% freedom from Fontan failure at 10-year follow-up and 77% at 20-year follow-up. In their cohort, AVV morphology was important. Two-thirds of patients with a common AVV and one-half of patients with a morphologic tricuspid valve experienced valve failure by age 30 years. Unfortunately, for patients who required AVV intervention before or at time of Fontan completion, 40% experienced AVV failure within a median of 3.5 years (1).
In a similar large cohort study, the Mayo Clinic experience with 1,052 patients identified 6% who had AVV replacement during the Fontan operation and an additional 7% who required AVV intervention after Fontan (2). In that cohort, AVV replacement during Fontan was associated with increased early mortality and need for re-operation. AVV intervention after Fontan was associated with morbidity from protein-losing enteropathy and arrhythmia, as well as early mortality (5). Similarly, when AVV intervention was required during Fontan conversion, it was associated with increased early mortality (6).
Patients with heterotaxy syndrome historically had high early and late mortality after Fontan (7). Surgical advancements successfully overcame many of the issues related to systemic and pulmonary venous anomalies. However, a common AVV is a risk factor in many studies for reduced transplant-free survival. The common AVV in heterotaxy patients has abnormal morphology with redundant leaflet tissue and an unusual subvalve chordal apparatus. It may deteriorate in early childhood, and consequently, AVV regurgitation is frequent. Similar to the experience of others, King et al. (1) found that the durability of a common AVV repair was not good, and many of these patients required valve replacement within 5 years of initial repair, usually in childhood.
King et al. (1) also found that a morphologic tricuspid valve had progressive deterioration after the Fontan operation in patients with mitral valve atresia. Although early mortality for patients undergoing a Fontan procedure in the current era is similar to those with right ventricular or left ventricular morphology, the fate of a systemic right ventricle during long-term follow-up is affected by the durability of the tricuspid valve in the systemic circulation.
Early studies described the Fontan procedure using the word “correction” in the article titles (8,9). The clinical doctrine of the 1970s to 1990s supported this early enthusiasm because all patients with functional single ventricle physiology were managed to achieve a Fontan operation. However, in the current era, after 40+ years of worldwide experience with this form of surgical palliation, it has become clear that there are a large number of patients who do not do well after a Fontan operation. Appropriate patient selection is essential to reduce the number of poor outcomes.
The excellent paper from King et al. (1) adds important data and experience to the field and shows that AVV regurgitation is a progressive valve disease. Can the systemic AVV in a Fontan circuit sustain patients for a lifetime? Unfortunately, the answer for nearly one-half of these patients appears to be no. However, those with Fontan physiology who thrive and live fairly normal lifestyles appear to have the best AV valves (1).
For those patients with progressive AVV regurgitation, despite previous attempts at valve repair, should a Fontan operation even be offered? What are other alternatives? Perhaps leave these patients with a bidirectional cavopulmonary connection and add a systemic to pulmonary artery shunt when cyanosis becomes extreme? The volume load created by a systemic to pulmonary artery shunt would likely hasten the demise of a ventricle that is already volume overloaded by significant AVV regurgitation. Alternatively, is early AVV replacement the correct path? Long-term data for early AVV replacement are lacking. Furthermore, anticoagulation of a mechanical AVV may be cumbersome in small children. Therefore, currently, there is no obvious solution to this dilemma, but as mechanical valve technology and novel anticoagulation therapies evolve, perhaps this will be a more rational approach in the future.
The concept of an interstage bidirectional Glenn procedure was initially proposed for patients with hypoplastic left heart syndrome. It was believed that this strategy would volume unload the functional single ventricle, preserve ventricular systolic and diastolic function, and, by extension, preserve AVV function. In many centers, the use of an interstage bidirectional Glenn procedure has been extended to all forms of a functional single ventricle. It would be informative to know if King et al (1). have sufficient data from this large cohort to assess if an interstage bidirectional Glenn procedure is related to AVV function.
Timing of intervention remains the major question for the large group of patients with AVV issues. Should it be addressed at time of the bidirectional Glenn, or as a separate stage between Glenn and Fontan, or during the Fontan? The answer to this clinical question is unclear, but AVV intervention after the Fontan procedure has suboptimal results. We can speculate that earlier AVV intervention in patients with functional single ventricle physiology, perhaps at the first signs of more than mild regurgitation, may improve long-term outcome. A large, global, Fontan registry−based evaluation of this question may provide us some insight. Meanwhile, clinicians should recognize that AVV disease in these fragile patients is progressive and warrants meticulous surveillance, and perhaps, earlier intervention.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
- King G.,
- Ayer J.,
- Celermajer D.,
- et al.
- Pundi K.N.,
- Johnson J.N.,
- Dearani J.D.,
- et al.
- Choussat A.,
- Fontan F.,
- Besse P.
- Pundi K.N.,
- Pundi K.N.,
- Johnson J.N.,
- et al.
- Bartz P.J.,
- Driscoll D.J.,
- Dearani J.D.,
- et al.