The Impact of Pulmonary Insufficiency on the Right Ventricle: A Comparison of Isolated Valvar Pulmonary Stenosis and Tetralogy of Fallot

Pulmonary insufficiency (PI) is associated with right ventricular (RV) dilation, dysfunction, and exercise intolerance in patients with tetralogy of fallot (TOF). We sought to compare RV function and exercise performance in patients with valvar pulmonary stenosis (VPS) following pulmonary balloon valvuloplasty to those with repaired TOF with similar degrees of PI. We performed a cross-sectional study of patients with VPS and TOF. Cardiac magnetic resonance (CMR) and exercise stress test were performed. Subjects were matched by time from initial procedure and severity of PI using propensity scores. After matching, there were 16 patients with VPS and 16 with TOF for comparison, with similar demographics. Time from initial procedure was 14 years (12–16), p = 0.92, and pulmonary regurgitant fraction was 19 % (6–31), p = 0.94, Patients with TOF had lower ejection fraction [58 % (53–66) vs. 65 % (60–69), p = 0.04] and more RV hypertrophy [69 g/m² (52–86) vs. 44 g/m² (32–66), p = 0.04] compared to those with VPS. Aerobic capacity was worse in patients with TOF [68 ± 19 % mVO2 (56–84) vs. 82 ± 9.2 % (74–89) in VPS, p = 0.01], with a trend for less habitual physical activity [0.9 (0–12) vs. 8 h/week (4–12), p = 0.056], respectively. With similar degrees of PI, patients with TOF demonstrate worse RV function and aerobic capacity as compared to patients with just VPS. Habitual exercise may in part explain differences in exercise performance and should be further explored.