Background:
Individuals with repaired tetralogy of Fallot (rTOF) often develop progressive pulmonary regurgitation (PR) and right ventricular (RV) dilation after initial repair, placing them at risk of arrhythmia, right heart failure, and sudden cardiac death. MRI research has led to body surface area (BSA)-indexed RV end-diastolic volume cutoffs (RVEDV>160ml/m2) for timing of pulmonary valve replacement (PVR), a strategy potentially limited by rising rates of obesity in this population.
Hypothesis:
Indexing RV volumes to actual BSA may underestimate disease progression in overweight patients.
Methods:
This retrospective analysis identified adults with rTOF and significant PR who underwent MRI for evaluation of RVEDV prior to consideration of PVR. Charts were reviewed for major adverse clinic events including death, heart failure, and sustained arrhythmia. Chamber volumes were indexed to BSA, as well as ideal BSA (defined by weight set to achieve BMI of 25).
Results:
58 adults with rTOF who met inclusion criteria were identified; 43% were overweight (BMI>25). Compared with normal weight individuals, overweight patients were older at MRI (44±12 vs 30±10 years, p<0.001) and definitive repair (9±8 vs 3±3 years, p=0.002), and more likely to have staged repair (56% vs 24%, p=0.01). Overweight patients had more advanced RV (RVEF 40±11% vs 55±33%, p=0.03) and LV (LVEF 53±12% vs. 59±13%, p=0.02) systolic dysfunction, as well as larger LVEDV (84±26 vs 65±15ml/m2, p=0.001) and RVEDV (152±50 vs 139± 61ml/m2, p=0.37) when indexed to ideal BSA. Overweight patients had higher incidence of arrhythmia (58% vs 20%, p=0.04), and decompensated HF (15% vs 0%, p=0.06) prior to MRI. Indexing RVEDV to ideal BSA in the overweight population led to reclassification of 4 patients meeting criteria for PVR (15 vs 11, p<0.001) meeting established criteria for PVR (RVEDV>160ml/m2), 3/4 of whom had clinical arrhythmia prior to MRI.
Conclusions:
Overweight patients with rTOF not only demonstrate advanced biventricular remodeling, but also experience negative clinical outcomes. Indexing RV volume to actual BSA may underestimate chamber size, whereas indexing to ideal BSA may identify high risk patients at risk for cardiac outcomes who could benefit from PVR.