Resumen de Patients With Heart Failure in the "Intermediate Range" of Peak Oxygen Uptake: ADDITIVE VALUE OF HEART RATE RECOVERY AND THE MINUTE VENTILATION/CARBON DIOXIDE OUTPUT SLOPE IN PREDICTING MORTALITY.

Luiz E. Ritt, Ricardo Brandao Oliveira, Jonathan Myers, Ross Arena, Mary Ann Peberdy, Daniel Bensimhon, Paul Chase, Daniel Forman, Marco Guazzi

• PURPOSE: While patients with heart failure who achieve a peak oxygen uptake (peak O2) of 10 mL[middle dot]kg-1[middle dot]min-1 or less are often considered for intensive surveillance or intervention, those achieving 14 mL[middle dot]kg-1[middle dot]min-1 or more are generally considered to be at lower risk. Among patients in the "intermediate" range of 10.1 to 13.9 mL[middle dot]kg-1[middle dot]min-1, optimally stratifying risk remains a challenge.

  METHODS: Patients with heart failure (N = 1167) referred for cardiopulmonary exercise testing were observed for 21 +/- 13 months. Patients were classified into 3 groups of peak o2 (<=10, 10.1-13.9, and >=14 mL[middle dot]kg-1[middle dot]min-1). The ability of heart rate recovery at 1 minute (HRR1) and the minute ventilation/carbon dioxide output ( E/ co2) slope to complement peak o2 in predicting cardiovascular mortality were determined.

  RESULTS: Peak o2, HRR1 (<16 beats per minute), and the E/ co2 slope (>34) were independent predictors of mortality (hazard ratio 1.6, 95% CI: 1.2-2.29, P = .006; hazard ratio 1.7, 95% CI: 1.1-2.5, P = .008; and hazard ratio 2.4, 95% CI: 1.6-3.4, P < .001, respectively). Compared with those achieving a peak o2 >= 14 mL[middle dot]kg-1[middle dot]min-1, patients within the intermediate range with either an abnormal E/ co2 slope or HRR1 had a nearly 2-fold higher risk of cardiac mortality. Those with both an abnormal HRR1 and E/ co2 slope had a higher mortality risk than those with a peak o2 <= 10 mL[middle dot]kg-1[middle dot]min-1. Survival was not different between those with a peak o2 <= 10 mL[middle dot]kg-1[middle dot]min-1 and those in the intermediate range with either an abnormal HRR1 or E/ co2 slope.

  CONCLUSIONS: HRR1 and the E/ co2 slope effectively stratify patients with peak o2 within the intermediate range into distinct groups at high and low risk.