Exercise anaerobic threshold and Ventilatory efficiency identify heart failure patients for high risk of early death

Background-The maximal oxygen uptake (peak (V) over dotO(2)) is used in risk stratification of patients with chronic heart failure (CHF). Peak (V) over dot O-2 might be lower than maximally possible if exercise is stopped early because of lack of patient motivation or premature cessation by the investigator. In contrast, the anaerobic threshold ((V) over dot O(2)AT) and the ventilatory efficiency ((V) over dot versus (V) over dot CO2 slope) are less subject to these influences. Thus, we compared these parameters with peak (V) over dot O-2 in identifying patients with CHF at increased risk for death within 6 months after evaluation. Methods and Results-We performed cardiopulmonary exercise tests with gas exchange measurements in 223 consecutive patients with CHF (114 coronary artery disease, 92 dilated cardiomyopathy, 17 others) at the Herzzentrum Ludwigshafen between 1995 and 1998. We measured peak (V) over dot O-2, (V) over dot O(2)AT and (V) over dot E versus (V) over dot CO2 slope. We selected peak (V) over dot O-2 of less than or equal to14 mL/kg per minute, (V) O(2)AT of < 11 mL/kg per minute, and (V) over dot E versus (V) over dot CO2 slope of >34 as threshold values for high risk of death. The median follow-up time was 644 days. Patients with peak (V) over dot O-2 of less than or equal to14 mL/kg per minute had Me V a >3-fold-increased risk (OR=3.4; CI, 1.3 to 9.1), with (V) over dot O(2)AT <11 mL/min per kg or (V) over dot E versus (V) over dot CO2 slope >34 a 5-fold increased risk for early death (OR=5.3; CI, 1.5 to 19.0; OR=4.8; CI, 1.7 to 13.8, respectively). In patients with both (V) over dot O(2)AT <11 mL/kg per minute and (V) over dot E versus (V) over dot CO2 slope >34, the risk of early death was 10-fold higher (OR=9.6; CI, 2.1 to 44.7). After correction for age, sex, left ventricular ejection fraction, and New York Heart Association class in a multivariate analysis, the combination of (V) over dot O(2)AT <11 mL/kg per minute and (V) over dot E versus (V) over dot CO2 slope >34 was the best predictor of 6-month mortality (RR=5.1, P=0.001). Conclusions-(V) over dot O(2)AT of <11 mL/kg per minute and slope of (V) over dot E versus (V) over dot CO2 >34, combined, better identified patients at high risk for early death from CHF than did peak (V) over dot O-2 and should therefore be considered when prioritizing patients for heart transplantation.