Abstract 14584: Exercise Capacity and Stroke Volume are Preserved Even with a Severely Dilated Right Ventricle, Late After Tetralogy Repair
Introduction: Pulmonary regurgitation (PR) with progressive right ventricle (RV) dilatation is very common late after repair of Tetralogy of Fallot (TOF) in childhood. Guidelines recommend pulmonary valve replacement (PVR) when indexed RV end diastolic volume (RVEDVi) exceeds 150ml/m2, even in asymptomatic patients. As PVR, however, has limited durability, this should be deferred as long as possible. We compared subjects with RVEDVi below versus above this cut-point, measuring cardiac function and exercise capacity objectively.
Hypothesis: That left ventricular (LV) stroke volume and exercise capacity deteriorate when RVEDVi increases above 150ml/m2, in patients with repaired TOF.
Methods: Of 60 patients with repaired TOF (mean age at repair 2.6 ± 2.5 years; age at MRI study 24.5 ± 9.5 years; range 11 to 48 years; 36 males), 32 had RVEDVi below and 28 had RVEDVi above 150ml/m2, at time of referral. Cardiac MRIs (1.5T) and cardiopulmonary exercise tests were performed.
Results: In the >150ml/m2 group, RVEDVi was 185 ± 38 ml/m2 compared to 117 ± 23 ml/m2 in the other subjects (p=0.0001). RV ejection fraction was lower (47 ± 7% vs 52 ± 7%, p=0.0066), fractional PR was higher (41 ± 12% vs 24 ± 14%, p=0.0001) but RV stroke volume was larger (154 ± 33 ml vs 107 ± 27 ml, p=0.0001) in the >150ml/m2 group. There were no significant differences in LV stroke volume (86 ± 17 ml vs 77 ± 21 ml, p=0.06), LV ejection fraction (57 ± 7% vs 56 ± 7%, p=0.86) or exercise capacity (% predicted Wpeak: 92 ± 20% vs 89 ± 17%, p=0.50 and; % predicted VO2peak: 84 ± 18% vs 88 ± 16%, p=0.44). Fibrosis was rarely detected in the RV body (n=1) and more frequently in the RV outflow (n=33, p=NS).
Conclusions: Exercise capacity and stroke volume are maintained with RVEDVi above compared to below the currently recommended cut-off for PVR surgery. Optimal timing for PVR thus remains unclear, given these observations.
- Tetralogy of Fallot
- Pulmonary valve
- Adult congenital heart disease
- Exercise tests
- Magnetic resonance imaging
- © 2011 by American Heart Association, Inc.