Modest Increase in Peak VO 2 Is Related to Better Clinical Outcomes in Chronic Heart Failure Patients

Abstract

Background— The prognostic ability of a single measurement of peak oxygen uptake (VO 2 ) is well established in patients with chronic heart failure. The relation between a change in peak VO 2 and clinical outcomes is not well defined. Methods and Results— This investigation determined whether an increase in peak VO 2 was associated with a lower risk of the primary end point of time to all-cause mortality or all-cause hospitalization and 3 secondary end points. In Heart Failure and a Controlled Trial to Investigate Outcomes of Exercise Training, an exercise training trial for patients with systolic heart failure, cardiopulmonary exercise tests were performed at baseline and ≈3 months later in 1620 participants. Median peak VO 2 in the combined sample increased from 15.0 (11.9–18.0 Q1–Q3) to 15.4 (12.3–18.7 Q1–Q3) mL·kg −1 ·min −1 . Every 6% increase in peak VO 2, adjusted for other significant predictors, was associated with a 5% lower risk of the primary end point (hazard ratio=0.95; CI=0.93–0.98; P <0.001); a 4% lower risk of the secondary end point of time to cardiovascular mortality or cardiovascular hospitalization (hazard ratio=0.96; CI=0.94–0.99; P <0.001); an 8% lower risk of cardiovascular mortality or heart failure hospitalization (hazard ratio=0.92; CI=0.88–0.96; P <0.001); and a 7% lower all-cause mortality (hazard ratio=0.93; CI=0.90–0.97; P <0.001). Conclusions— Among patients with chronic systolic heart failure, a modest increase in peak VO 2 over 3 months was associated with a more favorable outcome. Monitoring the change in peak VO 2 for such patients may have benefit in assessing prognosis. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00047437.