Is there a role for mechanical valve prostheses in pulmonary valve replacement late after tetralogy of Fallot repair?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: What is the role of mechanical valve prostheses in pulmonary valve replacement late after tetralogy of Fallot (TOF) repair? Altogether more than 30 papers were found using the reported search, of which 9 represented the best evidence to answer the clinical question. In addition to this, two papers were found by searching the reference lists of the relevant papers. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude from the best evidence available that mechanical prosthetic valves do play a role in patients who require pulmonary valve replacement late after repair of TOF. With adequate anticoagulation, they represent a safe alternative to biological valves. Although the literature is very limited, in terms of patient numbers, many of the papers demonstrate an acceptable early mortality rate. There is significant variability in the regimes of anticoagulation in these patients, and the overall reported rate of valvar thrombosis, thromboembolic events and major haemorrhagic complications has also been variable. The overall rate of valvar thrombosis and other thromboembolic events is promising. Thrombotic events were often attributed to poor adherence to the anticoagulation regime. Conversely, 3 papers recorded no thromboembolic events during the follow-up period. Three papers recorded major haemorrhagic events during their follow-up period and concluded that these were a rare outcome. When appropriate anticoagulation is adhered to, mechanical pulmonary prostheses appear to be relatively safe in patients late after repair of TOF. We have also found that the rationale for insertion of mechanical valves in the pulmonary position late after TOF repair varies across centres is still controversial. Furthermore, their use in patients with concomitant pulmonary arterial stenoses may be less advisable as this will prevent future percutaneous interventions of the pulmonary arterial tree. More research is required to accurately compare the haemodynamic properties of mechanical valves in the pulmonary position compared with other valves. Additionally, a more consistent follow-up of these patients in terms of echocardiographic, valve-related and warfarin-related complications is needed. With this information, clearer conclusions may be drawn when considering their role.