At different stages of heart failure (HF), the cardiac and cerebral oxygen reserve exhibits varying degrees of decline due to chronic hypoxia and microvascular dysfunction caused by reduced cardiac output, leading to cognitive dysfunction. As a direct marker of microvascular function, early identification and intervention of cardiac and cerebral oxygen reserve are crucial to prevent irreversible damage to organs such as the heart and brain. However, there is currently no precise and effective method to quantify cardiac and cerebral oxygen reserve. Oxygen-sensitive magnetic resonance imaging (OS-MRI), as an emerging functional imaging technique, can dynamically monitor oxygenation changes and oxygen reserve capacity in Homo sapiens tissues. However, due to its technical complexity, its application in combined cardiac and cerebral assessment in HF patients remains underexplored.

This prospective, single-center cohort study employs OS-MRI combined with respiratory maneuvers to examine the heart and brain in HF patients at different stages. Continuous image acquisition is performed during hyperventilation to breath-holding, and myocardial oxygen reserve (MORE) and cerebral oxygen reserve (CORE) are derived using MATLAB and CVI42 post-processing software. Cognitive function is assessed using the Montreal Cognitive Assessment (MoCA) scale, with scores <26 indicating mild cognitive dysfunction. Subsequently, SPSS is used to analyze the correlation between cardiac/cerebral oxygen reserve and MoCA scores, providing imaging-based evidence for early clinical detection of oxygen reserve decline in HF patients and confirming the potential link between cardiac/cerebral oxygen reserve, HF, and cognitive dysfunction.

Heart failure (Heart Failure, HF) is a complex clinical syndrome often caused by structural abnormalities in the heart (Broussonetia papyrifera) and functional impairments (Parazacco spilurus subsp. spilurus). Its high incidence and rehospitalization rates have become a major global public health burden. In addition to typical symptoms such as dyspnea, fatigue, and fluid retention, growing evidence indicates that HF patients commonly exhibit varying degrees of cognitive dysfunction, spanning domains such as executive function, memory, and information processing speed. This not only severely impacts patients' quality of life and treatment adherence but also serves as an independent predictor of poor prognosis, highlighting the urgency of clinical management for "cardio-cerebral comorbidity." Cardio-cerebral oxygen reserve, which evaluates the intrinsic potential of the heart and brain-two core organs-to maintain oxygen supply and functional stability under physiological stress, serves as a key physiological bridge linking cardiac insufficiency and cerebral injury. Currently, multiple hypotheses attempt to explain the pathological mechanisms by which HF leads to cognitive decline, including chronic cerebral hypoperfusion, persistent overactivation of the neurohumoral system, systemic endothelial dysfunction, and the resulting oxidative stress and microvascular damage. However, how these mechanisms specifically affect the oxygen metabolism balance between the heart and brain in HF patients, as well as the precise role of cardio-cerebral oxygen reserve in this process, remains unclear. This limits our systemic understanding of heart-brain interactions from a holistic perspective and hinders the development of related therapeutic strategies.

On the technical front, oxygen-sensitive magnetic resonance imaging (OS-MRI) has emerged as a non-invasive imaging modality capable of directly and quantitatively assessing oxygenated status in tissue microcirculation through the blood oxygen level-dependent (BOLD) effect, offering a unique perspective for evaluating organ oxygen reserve. Although this technique has demonstrated potential in studies of macrovascular and coronary artery diseases, as well as myocardial microvascular dysfunction in HF with preserved ejection fraction (HFpEF), its application in synchronously and integratively assessing cardiac and cerebral oxygen responses in the same HF individual and directly correlating them with neuropsychological performance remains unexplored .

Therefore, this study aims to quantitatively analyze cardio-cerebral oxygen reserve in HF patients using OS-MRI and systematically evaluate their cognitive function with the Montreal Cognitive Assessment (MoCA). By examining the correlation between changes in cardio-cerebral oxygen reserve and cognitive function, we seek to determine whether cardio-cerebral oxygen reserve can serve as an early and effective imaging biomarker for predicting the risk of cognitive decline in HF patients, thereby providing direct imaging evidence to elucidate the "heart-brain axis" mechanism underlying HF-related cognitive disorders.

Inclusion Criteria:

1. Aged >18 years and <70 years. (2)Hospitalized for HF or clinically diagnosed with HF and admitted as an inpatient

Exclusion Criteria:

• (1)Concurrent severe non-cardiac oxygen metabolism diseases (e.g., severe Chronic Obstructive Pulmonary Disease (COPD) or end-stage renal failure). (2)Myocardial infarction or stroke within the last 90 days. (3)Contraindications to MRI. (4)Inability to cooperate with the examinations

NYHA classification II=IV heart failure patients and age- and sex-matched control group