Remote Ischaemic Conditioning (RIC) in Heart Failure

Inclusion Criteria: * Age \>18 years * Ability to provide written consent * clinical diagnosis of HFpEF (LVEF ≥50%; symptoms and signs of heart failure \[HF\] caused by a structural and/or functional abnormality, and at least one: elevated natriuretic peptides; ambulatory; BNP ≥35 pg/mL or NT-proBNP ≥125 pg/mL or hospitalised; BNP ≥100 pg/mL or NT-proBNP ≥300 pg/mL, and objective evidence of cardiogenic pulmonary or systemic congestion) OR stable type 2 diabetes (determined by formal diagnosis in hospital or GP case records with diagnostic oral glucose tolerance test or glycated haemoglobin level ≥6.5%) and with ACC/AHA stage B HF (structural disorder of the heart but no current or previous symptoms of HF) OR confirmed diagnosis of dilated cardiomyopathy Exclusion Criteria: * Absolute contraindications to MRI or contrast (e.g. severe claustrophobia, pregnancy, ferromagnetic implants, inability to lie flat, severe renal impairment eGFR\<30ml/min/m2) * Moderate to severe valvular heart disease * Confirmed coronary artery disease (\>50% narrowing in any major epicardial coronary artery on invasive or computed tomography coronary angiography, previous myocardial infarction, previous percutaneous intervention or coronary bypass surgery) * Known arterial stenosis of the upper extremity