Peak oxygen consumption as a predictor of death in patients with heart failure receiving beta-blockers

Abstract

Background: Peak oxygen uptake (peak VO2) is a strong predictor of mortality and is commonly used in the evaluation of patients for cardiac transplantation. Beta-blockers reduce mortality in patients with heart failure, without influencing peak VO2, raising the possibility that peak VO2 is no longer suitable as an indicator of prognosis in these patients.

Methods and results: We analyzed prospectively gathered data on 2105 patients referred for cardiopulmonary testing for all-cause mortality and for occurrence of death or transplantation. Patients receiving beta-blockers were younger, more likely to have coronary disease, and had a greater mean ejection fraction but had a similar peak VO2. There were 555 deaths (26%) and 194 (9%) transplants during a median follow-up of 3.5 years. Peak VO2 was a predictor of mortality irrespective of beta-blocker use; a decrease of 1 mL x kg(-1) x min(-1) resulted in an adjusted hazard ratio (HR) of 1.13 (95% CI 1.09 to 1.17, P<0.0001) in patients not receiving beta-blockers and 1.27 (95% CI 1.18 to 1.36, P<0.0001) in patients receiving beta-blockers. Similar findings were noted when considering death or transplantation as an end point. Beta-blocker use was associated with better outcomes until peak VO2 values became very low (approximately 10 mL x kg(-1) x min(-1)), at which level survival rates were equally poor.

Conclusion: Peak VO2 is a determinant of survival in patients in heart failure even in the setting of beta-blockade. Because of improved survival in patients treated with beta-blockers, the cut point value of 14 mg x kg(-1) x min(-1) for referral for cardiac transplantation in these patients requires reevaluation, and a lower cut point may be more appropriate.