Omar M; Omote K; Sorimachi H; Popovic D; Kanwar A; Alogna A; Reddy YNV; Lim KG;Shah SJ; Borlaug BA;
European journal of heart failure [Eur J Heart Fail] 2023 Jun 14.
Date of Electronic Publication: 2023 Jun 14.
Background & Aims: It is widely held that heart failure (HF) does not cause exertional hypoxemia, based upon studies in HF with reduced ejection fraction (EF), but this may not apply to patients with HF and preserved EF (HFpEF). Here, we characterize the prevalence, pathophysiology, and clinical implications of exertional arterial hypoxemia in HFpEF.
Methods & Results: Patients with HFpEF (n=539) and no coexisting lung disease underwent invasive cardiopulmonary exercise testing with simultaneous blood and expired gas analysis. Exertional hypoxemia (oxyhemoglobin saturation <94%) was observed in 136 patients (25%). As compared to those without hypoxemia (n=403), patients with hypoxemia were older and more obese. Patients with HFpEF and hypoxemia had higher cardiac filling pressures, higher pulmonary vascular pressures, greater alveolar-arterial O 2 difference, increased dead space fraction, and greater physiologic shunt compared to those without hypoxemia. These differences were replicated in a sensitivity analysis where patients with spirometric abnormalities were excluded. Regression analyses revealed that increases in pulmonary arterial and capillary pressures were related to lower PaO 2 , especially during exercise. BMI was not correlated with the arterial PaO 2 , and hypoxemia was associated with increased risk for death over 2.8 (IQR 0.7-5.5) years of follow up, even after adjusting for age, sex, and BMI (HR 2.00 (95%CI: 1.01-3.96), p=0.046).
Conclusion: Between 10-25% of patients with HFpEF display arterial desaturation during exercise that is not ascribable to lung disease. Exertional hypoxemia is associated with more severe hemodynamic abnormalities and increased mortality. Further study is required to better understand the mechanisms and treatment of gas exchange abnormalities in HFpEF.