Abstract 14471: The Value of Cardiopulmonary Exercise Testing in Establishing Prognosis in Valvular Heart Disease

Abstract

Introduction: Cardiopulmonary exercise testing (CPX) is used to establish prognosis in heart failure with both peak oxygen uptake (peak VO2) and the nadir of the ventilatory equivalent for carbon dioxide (VE/VCO2 nadir) predicting short-term outcomes, but CPX has not been widely employed in evaluating patients with valvular heart disease (VHD). Hypothesis: Peak VO2 and VE/VCO2 nadir will predict mortality in VHD.

Methods: We analyzed our CPX database for patients with VHD during the period of 11-1-07 through 3-12-12 and extracted clinical and exercise data. Mortality was determined from the National Death Index through 3-14-2012. We divided peak VO2 and VE/VCO2 nadir into 5 classes by established norms and calculated mortality during follow-up for each class. Cox Proportional Hazards regression with age, sex, and other potential predictors of mortality was used to determine the independent significance of peak VO2 and VE/VCO2 nadir is predicting mortality. Significance was set at p < 0.05.

Results: We identified 1788 unique patients (711 women = 40%) with left-sided VHD. Age was 61 ± 15 years. Aortic VHD was present in 48% and mitral VHD in 62%, so 10% had combined aortic + mitral VHD. There were 98 deaths during follow-up of 675 ± 425 days, none within 48 hours of CPX. Peak VO2 was 19.2 ± 7.2 mL/kg/min or 72 ± 22% of age-sex predicted. VE/VCO2 nadir was 30.4 ± 5.6. Mortality decreased progressively with increasing peak VO2 from 21.6% at < 10 mL/kg/min to 1.6% at ≥ 22 mL/kg/min. Mortality increased progressively with increasing VE/VCO2 nadir from 2.0% at < 30 to 35.3% at ≥ 45. Peak VO2 and VE/VCO2 nadir remained significant in the Cox regression with hazard ratios [95% CI, p] of 0.851 [0.805-0.900, p <0.001] and 1.041 [1.008-1.076, p = 0.0158], respectively. Sex and history of heart failure were other significant predictors of mortality.

Conclusion: CPX with specific determination of peak VO2 and VE/VCO2 nadir is a powerful tool for predicting short-term mortality across in left-sided VHD.