Arterial Stiffness and Endothelial Function in Heart Failure

Inclusion Criteria: * Male and female ≥ 18 years old. * Have a confirmed de-novo diagnosis of Heart failure with preserved ejection fraction or Heart failure with reserved ejection fraction. Common HF phenotypes (e.g., hypertension, diabetes, obesity) will be recorded as part of routine baseline data but will not influence recruitment or sampling. . * Have stable Heart failure in the opinion of the investigator. * Have ability, in the opinion of the investigator, to participate in study activities. * Able to provide written informed consent. Exclusion Criteria: * • Inability to provide verbal informed consent. * Presenting with severe symptoms; major co-morbidity or other alternative diagnoses (e.g., malignancy, severe respiratory disease, severe mental health problem/s). * Recent acute coronary syndrome (within 60 days). * Severe physical disability preventing independence. * Severe renal insufficiency. * Pregnancy (Present or planned). * Life expectancy less than 12 months