BACKGROUND: Free pulmonary regurgitation (PR) after surgical correction of Tetralogy of Fallot (ToF) with transannular patching can lead to irreversible right ventricular (RV) failure. However, the optimal timing of valve replacement is still debated.

METHODS AND RESULTS: Thirty six pigs were included in the study. Twenty one pigs had a bare metal stent placed in the pulmonary annulus inducing free PR and 9 animals served as control. Six animals died prematurely due to procedural complications. The 21 animals were divided into 3 groups with differential duration of PR (1, 2, 3 months, respectively) after which PPVR was performed. After 1 month with competent valve the animals were euthanized. Cardiac magnetic resonance (CMR) and right heart catheterization were performed serially. Free PR led to severe dilation of the RV in all three groups compared to matched controls (p<0.001). Final RV volume after one month with competent pulmonary valve was modeled. Increase in RV volume from baseline to valve replacement (ΔRV) was the only predictor of RV recovery (p<0.001) and increases in ΔRV beyond 120 mL/m2 were predictive of very low probability of recovery. A total of 5 animals did not recover.

CONCLUSIONS: Recovery of right ventricular function after free PR by treatment with PPVR was successful in the majority of animals. Increases in RV volume during PR were the only predictor of non-recovery after PPVR and duration of PR did not in itself predict treatment success.