The goal of this observational study is to determine whether changes in the inflammatory profile of heart failure patients can help identify those who may have a worse prognosis or who might benefit more from specific treatments. In addition, we aim to explore whether certain genes or gene mutations are related to a higher risk of future cardiovascular problems.

Heart failure continues to be a major cause of hospital admissions and death in our society. Because of this, it is very important for healthcare professionals to identify which patients are at higher risk of complications, so that we can provide the best possible treatment and follow-up. One method we use to help predict how the disease may evolve is the study of biomarkers, which are measurable biological substances that can help detect, monitor, or treat illnesses in a more personalized way.

In this study, the investigators will measure mainly inflammatory biomarkers that will be analyzed from a blood sample taken during hospital stay after being diagnosed with heart failure with preserved or mildly reduced ejection fraction. Any important health events that happen during the next six months after patients are discharged from hospital will also be recorded.

In addition, it is known that more than 2,000 diseases are known to be caused by changes in specific genes. In the case of cardiomyopathies-heart muscle diseases that can lead to heart failure-genetic causes vary depending on the type, and studies suggest that between 10% and 50% of cases may have a genetic origin. Identifying genetic markers linked to heart failure with preserved or mildly reduced ejection fraction may help improve prevention, treatment, and risk assessment, as some genetic changes may be associated with repeated cardiovascular events. By studying not only circulating biomarkers but also genetic factors, the investigators hope to better understand whether certain gene alterations may increase a person's tendency to experience additional heart-related events.

This is an observational study, which means that medical care and treatment will be exactly the same whether patients choose to participate or not. Participation involves allowing researchers to collect relevant information from medical records and agreeing to the collection of two or three small additional blood samples for research purposes. These samples will be used to measure the biomarkers and to analyze genes in the white blood cell fraction obtained from the same tubes.

Inclusion Criteria:

• Age ≥18 years at recruitment.

• Signed informed consent.

• Hospitalization due to decompensated heart failure, based on Framingham criteria and elevated natriuretic peptides (N-terminal of the prohormone brain natriuretic peptide (NT-proBNP) ≥450 pg/ml, or ≥900 pg/ml for patients with atrial fibrillation or flutter).

• Left ventricular ejection fraction(LVEF) ≥40% and evidence of structural heart disease based on the presence of at least one of the following imaging criteria:

  • Left atrial dilation: LA diameter ≥3.8 cm, or area ≥20 cm², or LA volume ≥55 ml, or indexed LA volume ≥29 ml/m².
  • Left ventricular hypertrophy, defined as septal or posterior wall thickness ≥1.1 cm.
  • Evidence of increased filling pressures, measured by septal or lateral E/e' ratio >15 or >12, respectively.

Exclusion Criteria:

• Hemodynamic instability at the time of inclusion.

• Heart failure secondary to acute myocardial infarction (AMI).

• Pregnant or breastfeeding women.

• Comorbidities that could influence the clinical course:

  • COPD requiring long-term home oxygen therapy, oral corticosteroids, hospitalization due to exacerbation, or primary pulmonary arterial hypertension.
  • Chronic treatment with immunosuppressants, corticosteroids, or IL-1 antagonists within the 6 months prior to inclusion.
  • Confirmed active infection or patients currently receiving antibiotic treatment.
  • Acute or chronic liver disease.
  • Chronic kidney disease with eGFR <15 ml/min/1.73 m² or need for dialysis during hospitalization.
  • Hematological disorders, such as blood dyscrasias or hemoglobin <9 g/dl on admission.
  • Active oncological disease, except treated basal cell carcinoma or low-risk prostate cancer.
  • Patients with limb amputation or carriers of pacemakers or defibrillators (due to possible errors in BIA measurements).
  • Any disease associated with a life expectancy of less than one year, or patients expected to have difficulty adhering to the study protocol

• Patients actively participating in other clinical trials involving investigational drugs at the time of inclusion.

All patients hospitalized for HF at the FundaciJiménez Díaz University Hospital (Madrid), with preserved or slightly reduced LV ejection fraction (LVEF ≥40%), with evidence of structural heart disease (left atrial dilation or left ventricular hypertrophy) and elevated natriuretic peptides.