Abstract 3102: Impact of Body Fat Adjusted Peak Oxygen Consumption on Predicting Survival in Patients with Advanced Heart Failure
Numerous studies have demonstrated the impact of peak oxygen consumption (PkVO2) in predicting prognosis in advanced heart failure (HF), where a value < 14 ml/kg/min is traditionally used as a cut-point reflecting poor survival. We have previously demonstrated the superiority of lean adjusted PkVO2 (PkVO2lean) using a cut-point of < 19 ml/kg/min in predicting subsequent death and/or transplantation in a relatively small cohort of HF patients. We sought to evaluate this parameter against the traditional cut-point of 14 ml/kg/min in a larger cohort of advanced HF patients (n =875;56 ± 13 years;71% male) utilizing the sole and stronger endpoint of all-cause mortality. After a mean follow-up of 3.0 ±1.8 years, there were 118 deaths (13%). Compared with survivors, those who died had higher age (61±11 vs 55±13 years, p<0.0001), % male (82% vs 70%, p < 0.01), BNP (527±568 vs 334 ±448 pg/ml, p<0.01), and lower ejection fraction (22 ±9 vs 24±9%, p<0.01) and creatinine clearance (77±35 vs 88±36 mg/dl, p< 0.01). Survivors also had higher levels of both PkVO2 (16.1±5.8 vs 13.0±4.1 ml/kg/min, p<0.0001) and PkVO2lean (22.7±7.4 vs 17.9 ±5.6 ml/kg/min, p<0.0001). Both groups were statistically similar regarding serum sodium and hemoglobin concentrations. By multiple regression, using 7 independent variables, PkVO2lean (t=2.6, p<0.01) and BNP (t=3.2, p<0.01) were strong independent predictors of survival, whereas PkVO2 was not (t=1.5, p=0.14). By actuarial hazard analysis, a 19 ml/kg/min cut-point for PkVO2lean was a better determinant of time-dependent survival (Chi-square = 33) than was the traditional cut-point of 14 ml/kg/min of PkVO2 (Chi square = 23).
Conclusion: Lean adjusted PkVO2 is superior to the traditional total weight adjusted PkVO2 in predicting survival in HF patients. Assessment of percent body fat and determination of lean body mass should be incorporated into the routine performance of cardiopulmonary stress testing in HF patients.