The applications and potential limitations of right ventricular volumes as surrogate marker in tetralogy of fallot

Cardiac magnetic resonance imaging derived right ventricular (RV) volumes are often necessary for optimal timing of pulmonary valve replacement in patients with tetralogy of Fallot (TOF). This practice is based on previous studies that reported preoperative RV volumetric thresholds that predicted postoperative RV remodeling. As a result, pulmonary valve replacements are being performed even in asymptomatic patients based on RV volumetric thresholds that predict complete postoperative RVOT remodeling. Hence, RV volumes are now being used as surrogate markers/endpoints for future cardiovascular outcomes. Unfortunately, there are no studies showing survival benefit for performing pulmonary valve replacement at smaller RV volumes. This review underscores some of the limitations of using RV volumes as surrogate markers for clinical outcomes, and also highlights knowledge gaps about the pathophysiologic mechanism of cardiovascular death in the TOF population.