Ventilatory Efficiency and Aerobic Capacity Predict Event-Free Survival in Adults With Atrial Repair for Complete Transposition of the Great Arteries

Objectives: The goal of this study was to assess the prognostic value of the cardiopulmonary exercise test (CPET) in patients who received a Mustard and Senning (M/S) operation. Background: Patients who received an M/S operation have increased long-term risk of cardiovascular morbidity and mortality. Limited information is available on how to stratify risk in this population. Methods: Between 1996 and 2007, 274 adults (age 26.3 ± 8.9 years, range 16 to 50 years) who had received a Mustard (n = 144) or Senning (n = 130) operation in infancy were studied with CPET. During a follow-up of 3.9 ± 2.3 years (range 0.2 to 10.8 years), 12 patients died at an age of 36 ± 14 years, and 46 patients required a cardiac-related emergency (<24 h from the onset of symptom/condition) hospital admission at an age of 30 ± 11 years. Results: At multivariate Cox analysis, the slope of ventilation per unit of carbon dioxide output (VE/VCO₂ slope) (hazard ratio: 1.088, p < 0.0001) and percentage of predicted peak oxygen uptake (Vo₂%) (hazard ratio: 0.979, p = 0.0136) were the strongest predictors of death/cardiac-related emergency hospital admission among demographic, clinical, and exercise variables. A VE/VCO₂ slope ≥35.4 (hazard ratio: 10.7, 95% confidence interval [CI]: 7.8 to 24.6), and a peak Vo₂% ≤52.3% (hazard ratio: 3.4, 95% CI: 2.5 to 8.2) were associated with an increased 4-year risk of death/cardiac-related emergency hospital admission. Patients who had both a VE/VCO₂ slope ≥35.4 and a peak Vo₂% ≤52.3% of predicted value were at highest risk (4-year event rate: 78.8%). Conclusions: CPET provides important prognostic information in adults with M/S operation. Subjects with enhanced ventilatory response to exercise or those with poor exercise capacity have a substantially higher 4-year risk of death/cardiac-related emergency hospital admission.