Abstract 4003: Improved Prognostic Assessment of Heart Failure Patients Using Resting Ventilatory Variability
Introduction: Ventilatory abnormalities are associated with increased morbidity and mortality in heart failure (HF) patients but identification via polysomnography is time consuming, not readily available, and expensive.
Hypothesis: We assessed the hypothesis that resting ventilatory variability (RVV) collected during a brief observation period prior to cardiopulmonary exercise testing could yield prognostic information in patients with HF.
Methods: RVV was collected prospectively in 399 successive patients for at least 5 min while they rested in Fowler’s position. RVV was determined as the percent change in resting ventilation from the highest and lowest values recorded during the last 4 min of rest. Follow-up lasted 10 years, an event was death or urgent transplant and other transplants were censored.
Results: After 10 years there were 148 patients alive, 195 deaths, 21 LVADs, 6 urgent transplants, and 29 other transplants. Significant univariate predictors (Chi Square) included VE/VCO2 slope (60.2), SBP≤100mm Hg (28.2), RVV (24.0), and peak VO2 (21.5). The Cox regression model that best described mortality was: Log VE/VCO2 slope (Hazard Ratio (HR) =62.2,p=0.00), SBP≤100mm Hg (HR=1.7,p=0.01), and RVV (HR=2.8,p=0.01). The model’s overall Chi Square was 100.3 compared to 86.4 without RVV. No other variables added to the model, including medications, invasive hemodynamics, resting end-tidal CO2 (32.0±4.3 mm Hg), resting respiratory rate (18±6 breaths•min−1), resting VO2 (3.6±1.5 ml·kg−1·min−1), peak VO2 (16.3±4.9 ml·kg−1·min−1), heart rate (81±16beats·min−1), age (51±10 years), and LVEF (22±8%).
Conclusions: RVV was a strong, independent predictor of mortality in this large group of HF patients. Further research is needed to determine the relationship between resting ventilatory variability and possibly related abnormalities such as heart rate variability, baroreflex sensitivity, sympathetic activation, and sleep disordered breathing.