Oscillatory Breathing and Exercise Gas Exchange Abnormalities Prognosticate Early Mortality and Morbidity in Heart Failure

Objectives The goal of this study was to identify better predictors of early death in patients with chronic left ventricular heart failure (CHF). Potential predictors, derived from cardiopulmonary exercise testing, were compared with other commonly used cardiovascular measurements. Background The prediction of early death in patients with CHF remains challenging. Methods Five hundred eight patients with CHF due to systolic dysfunction underwent resting cardiovascular measurements, 6-min walking tests, and cardiopulmonary exercise testing. The peak oxygen uptake ((V) over dotO(2)), peak oxygen pulse, anaerobic threshold, ratio of ventilation to carbon dioxide output ((V) over dotE/(V) over dotCO(2)), slope of (V) over dotE versus (V) over dotCO(2), and presence or absence of a distinctive oscillatory breathing pattern (OB) were ascertained. Outcomes were 6-month mortality and morbidity, the latter a sum of cardiac hospitalizations and deaths. Results The single best predictor of mortality was an elevated lowest (V) over dotE/(V) over dotCO(2) (>= 155% predicted). Adding OB on the basis of stepwise regression (optimal 2-predictor model), the odds ratio for mortality increased from 9.4 to 38.9 (p < 0.001). The slope of (V) over dotE versus (V) over dotCO(2) slope, peak (V) over dotO2, peak oxygen pulse, and anaerobic threshold combined with OB were also strong predictors. OB also increased the odds ratio 2-to 3-fold for each of these (p < 0.01). Kaplan-Meier survival curves and area under the receiver-operating characteristic curve confirmed that lowest (V) over dotE/(V) over dotCO(2) and OB were superior. For morbidity, elevated lowest (V) over dotE/(V) over dotCO(2) or lower peak (V) over dotO(2) with OB were the best predictors. No nonexercise measurements discriminated mortality and morbidity. Conclusions Cardiopulmonary exercise testing parameters are powerful prognosticators of early mortality and morbidity in patients with CHF, especially the optimal 2-predictor model of a combination of elevated lowest V. E/(V) over dotCO(2) and OB. (J Am Coll Cardiol 2010; 55: 1814-23) (C) 2010 by the American College of Cardiology Foundation