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) were independently associated with a larger decrease of RV volumes (RV end-diastolic volume: β=0.41; P<0.001). Receiver operating characteristic analysis revealed a cutoff value of 160 mL/m for normalization of RV end-diastolic volume or 82 mL/m 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 or RV end-systolic volume was <82 mL/m.

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