Cerebral saturation is associated with physical activity and post-discharge mortality in heart failure patients

Background The cross-sectional relationship between heart failure (HF) and cerebral oxygenation has been studied in the past but the prognostic significance of this relationship has been limited. Here, we aimed to assess the role of cerebral tissue oxygen saturation (SctO2) as a risk factor for HF mortality and rehospitalization as well as evaluate the association between SctO2 with physical activity in a Swedish prospective HF cohort. Methods Ninety-five patients hospitalized for HF (mean age 70 years; 21% women) were examined with near-infrared spectroscopy (NIRS) and screened for physical activity derived from questionnaires in the Swedish national public health survey. The median follow-up time to death and re-hospitalization was 1377 (interquartile range, 245–2392) and 293 (14–2363) days, respectively. Associations between SctO2 at rest, post-discharge mortality and re-hospitalization were analyzed using multivariable Cox regression analysis adjusted for age, sex, body-mass index, smoking, prevalence of atrial fibrillation, prevalence of diabetes and systolic blood pressure. The associations between SctO2 and self-reported physical activity were explored by using logistic regression analysis adjusted for the aforementioned risk factors. Results A total of 25 patients (26%) reported to be engaged in physical activity less than one hour throughout the week. In the fully adjusted Cox regression model, low SctO2 at rest was associated with post-discharge mortality (HR, 0.77; CI, 0.66–0.91; p=0.002). However, low SctO2 was not associated with post-discharge rehospitalization risk (HR, 0.94; CI, 0.88–1.01; p=0.092). In the fully adjusted logistic regression models, low SctO2 at rest was associated with decreased physical activity (<1h per week), (OR 1.22; CI, 1.05–1.42; p=0.01). Conclusion We have demonstrated that low cerebral tissue oxygen saturation at rest is associated with post-discharge mortality in patients hospitalized for HF, independently of traditional risk factors. In addition, low cerebral tissue oxygen saturation at rest is associated with low physical activity. These findings highlight the role of cerebral saturation as a risk factor for cardiovascular prognosis, as well as underline the potential importance of taking cerebral perfusion into account when treating for heart failure.