Usefulness of Magnetic Resonance Imaging to Guide Referral for Pulmonary Valve Replacement in Repaired Tetralogy of Fallot

The aim of this study was to determine if adult patients with repaired tetralogy of Fallot are being referred for pulmonary valve replacement (PVR) earlier on the basis of cardiac magnetic resonance imaging (CMR) parameters despite the absence of CMR-based recommendations in the American College of Cardiology and American Heart Association joint guidelines. Variables defined by the guidelines were analyzed in conjunction with CMR-based parameters across 3 groups defined by the release of the guidelines: (1) patients referred before the guidelines, (2) patients referred 0 to 3 years after the guidelines, and (3) patients referred ≥3 years after the guidelines. Seventy-nine patients were identified. No significant trend was observed in guideline-defined variables. Significant trends in indexed right ventricular end-diastolic volume (p = 0.034), indexed right ventricular end-systolic volume (p = 0.001), and the right ventricular ejection fraction (p = 0.005) were observed across groups. By multivariate regression, patients who underwent PVR ≥3 years after the release of the guidelines had a 29 ml/m2 smaller indexed right ventricular end-diastolic volume (p = 0.01) and a 33 ml/m2 smaller indexed right ventricular end-systolic volume (p <0.001) compared with patients who underwent PVR before the release of the guidelines. PVR 0 to 3 years after the guidelines was not a significant predictor of either indexed right ventricular end-diastolic volume (p = 0.93) or indexed right ventricular end-systolic volume (p = 0.18). Patients referred for PVR ≥3 years after the guidelines had significantly smaller CMR-based right ventricular volumes without significant trends in guideline-defined variables. Given the increased use of CMR to guide PVR referral, revisiting the guidelines to address appropriate use of CMR derived thresholds is indicated.