Relationship Between Exercise Oscillatory Ventilation Loop and Prognosis of Heart Failure

Background: The cardiopulmonary exercise test (CPX) is a tool for evaluating disease severity and limitations in activities of daily living in patients with cardiac disorders. However, few studies have evaluated the association between exercise oscillatory ventilation (EOV) severity and prognosis in heart failure (HF) patients with EOV. EOV severity can be evaluated by detecting endtidal CO2 pressure (PETCO2, an indicator of the arterial partial pressure of CO2 (PaCO2)) and minute ventilation, which is a reflection of the respiratory response to elevated CO2. We hypothesized that the magnitude of EOV severity can predict the severity and prognosis of cardiac disorders and aimed to validate this hypothesis. Methods and Results: In total, 2,043 patients who underwent symptom-limited maximal CPX between 2010 and 2016 were evaluated. We enrolled 70 patients who had HF with reduced ejection fraction (HFrEF) and EOV. The endpoint was cardiovascular death. During a median follow-up of 4.3 years, 34 participants died (48%). Those who died showed significantly larger EOV loop size and lower hemoglobin (Hb) levels than those who survived (17.3 +/- 7.0 cm(2) vs. 12.8 +/- 6.1 cm(2), P< 0.001; 12.2 +/- 1.2 g/dL vs. 13.2 +/- 2.9 g/dL, P 0.004). Cox regression analyses revealed Hb levels and EOV loop size as independent predictors of cardiovascular death in HFrEF patients with EOV. Conclusions: EOV loop size was associated with cardiovascular death of HFrEF patients with EOV.