Outcome in patients with heart failure is related to VE/VCO2 and the chronotropic index

In a study of 470 patients with heart failure, Kaplan-Meier plot shows that survival is reduced when VE/V_CO2 is increased to ≥44.7 (33 versus 10 percent for value <44.7) and the chronotropic index (CRI), which correlates with the peak heart rate during exercise, is reduced to ≤0.51 (27 versus 11 percent for CRI >0.51). The combination of VE/V_CO2 and CRI was associated with the highest risk of death.