Preoperative thresholds for pulmonary valve replacement in patients with corrected tetralogy of Fallot using cardiovascular magnetic resonance

Background - To facilitate the optimal timing of pulmonary valve replacement, we analyzed preoperative thresholds of right ventricular ( RV) volumes above which no decrease or normalization of RV size takes place after surgery. Methods and Results - Between 1993 and 2006, 71 adult patients with corrected tetralogy of Fallot underwent pulmonary valve replacement in a nationwide, prospective follow-up study. Patients were evaluated with cardiovascular magnetic resonance both preoperatively and postoperatively. Changes in RV volumes were expressed as relative change from baseline. RV volumes decreased with a mean of 28%. RV ejection fraction did not change significantly after surgery (from 42 +/- 10% to 43 +/- 10%; P=0.34). Concomitant RV outflow tract reduction resulted in a 25% larger decrease of RV volumes. After correction for surgical RV outflow tract reduction, higher preoperative RV volumes (mL/m(2)) were independently associated with a larger decrease of RV volumes (RV end-diastolic volume: beta = 0.41; P < 0.001). Receiver operating characteristic analysis revealed a cutoff value of 160 mL/m2 for normalization of RV end-diastolic volume or 82 mL/m(2) for RV end-systolic volume. Conclusions - Overall, we could not find a threshold above which RV volumes did not decrease after surgery. Preoperative RV volumes were independently associated with RV remodeling and also when corrected for a surgical reduction of the RV outflow tract. However, normalization could be achieved when preoperative RV end-diastolic volume was < 160 mL/m(2) or RV end-systolic volume was < 82mL/m(2).