Increased Dead Space Ventilation as a Contributing Factor to Persistent Exercise Limitation in Patients with a Left Ventricular Assist Device

Figures

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  Figure 1. Flowchart of study inclusion. Combined outcome: composite of cardiovascular rehospitalization and mortality. EF: left ventricular ejection fraction. Group: patients with reduced left ventricular ejection fraction with and without a left ventricular assist device. HFrEF: heart failure with reduced ejection fraction (without left ventricular assist device support). LVAD: left ventricular assist device. NTproBNP: N-terminal prohormone of brain natriuretic peptide. PETCO2: endtidal carbon dioxide as a surrogate for alveolar perfusion. TAPSE: tricuspid annular plane systolic excursion. VD/VT: dead space ventilation during exercise. VE/VCO2: minute ventilation per carbon dioxide production. VP: ventilatory power (the ratio of peak systolic pressure and VE/VCO2).

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  Figure 2. Discrimination between patients with (LVAD) and without (HFrEF) a left ventricular assist device with reduced left ventricular ejection fraction. Receiver operating characteristics showing the area under the curve (AUC).

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  Figure 3. Discrimination between patients with (LVAD) and without (HFrEF) a left ventricular assist device with reduced left ventricular ejection fraction. Nomogram of variables to discriminate between groups. NTproBNP: N-terminal prohormone of brain natriuretic peptide. PETCO2: endtidal carbon dioxide as a surrogate for alveolar perfusion. TAPSE: tricuspid annular plane systolic excursion. VD/VT: dead space ventilation during exercise.

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  Figure 4. Prediction of the composite endpoint cardiovascular rehospitalization and mortality. Receiver operating characteristics showing the area under the curve (AUC).

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  Figure 5. Nomogram of variables to predict the composite endpoint cardiovascular rehospitalization and mortality. HFrEF: patients with reduced left ventricular ejection fraction without an assist device. LVAD: patients with reduced left ventricular ejection fraction and a left ventricular assist device. VE/VCO2: minute ventilation per carbon dioxide production. VP: ventilatory power (the ratio of peak systolic pressure and VE/VCO2).

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  Figure 6. Peak oxygen consumption (VO2peak) to predict overall mortality. (a) Box plot to illustrate the relationship between VO2peak and overall mortality in the entire population. The optimal cut-off, determined by the Youden criterion, is 13.1 mL/min/kg. (b) Receiver operating characteristics showing the area under the curve (AUC). The dashed horizontal line represents the calculated cut-off based on the study population.