A trial to test reduction in renal nerve activity as a possible treatment for heart failure.

INTERVENTION: Renal Denervation (RDN) is a simple catheter procedure removing excess nerve signals to and from the kidneys. The renal denervation system consists of a small steerable treatment catheter and an automatically‐controlled treatment delivery generator. The treatment does not require open surgery. A guiding catheter is inserted through a tiny incision in the groin into the femoral artery to direct the treatment catheter to the renal arteries. The treatment catheter delivers high‐frequency radio waves, called RF waves, to 4–6 locations within each of the two renal arteries. The energy delivered is about 8 watts. This energy delivery aims to disrupt the nerves and lower blood pressure over a period of months. The procedure takes 40 ‐60 minutes. RDN has been able to reduce Blood Pressure (BP) in patients with high BP resistant to multi‐drug treatment. Through removing excess nervous drive to the kidneys, heart and circulation this treatment has promise in Heart Failure (HF). CONDITION: Heart Failure with Preserved Ejection Fraction PRIMARY OUTCOME: Reduction in left atrial volume index (LAVi) and/or left ventricular mass index (LVMi) on cardiac magnetic resonance imaging (cMRI) in Heart Failure with Preserved Ejection Fraction (HFPEF). SECONDARY OUTCOME: Exercise capacity and functional status as assessed by maximal oxygen consumption (VO2max) on cardiopulmonary exercise testing and by 6‐minute walk test. Improvement in ventricular‐vascular function as evaluated by echocardiographic measures of arterial elastance, Left Ventricular (LV) end‐systolic elastance, LV filling pressure, and LV diastolic stiffness. Quality of life as assessed by the Minnesota Living with Heart Failure (MLWHF) scores Reduced chocardiographic grade of diastolic dysfunction as assessed by Tissue Doppler E/e’, (a non‐invasive estimate of left atrial filling pressure). Reduction in the composite end‐point of death or re‐admission with Heart Failure. Reduction of biomarkers of cardiac load and interstitial fibrosis as assessed by plasma assays of markers of ventricular and atrial haemodynamic load and other neurohormones contributing to HF pathophysiology as well as cytokine markers of inflammation and remodelling and markers of cardiac fibrosis and a marker of cardiomyocyte loss. ; The benefits listed above for renal denervation will apply to those with and without hypertension INCLUSION CRITERIA: *Patients with HFPEF (based upon ESC diagnostic criteria) a. Symptoms and signs of heart failure; NYHA Class II or higher b. Left ventricular ejection fraction 50% or greater on echocardiography c. Echocardiographic evidence of left ventricular diastolic dysfunction (echo‐Doppler E/e’ > 15 ) AND/OR plasma NTproBNP > 220pg/ml. *Episode of acute decompensation (ADHF) requiring hospital admission within the 12 months prior to recruitment *Patients with and without background hypertension may be recruited. In the case of patients with background hypertension (ie history of fulfilling the diagnostic WHO criteria for hypertension: SBP > 140 mmHg and/or DBP > 90 mmHg) those with both controlled (<140/90mmHg by 24 hour ambulatory BP) and inadequately controlled BP (on 3 anti‐hypertensive drugs including a diuretic) can be recruited.