This study will assess the efficacy of mirabegron, a new beta3-adrenergic receptor in the prevention of heart failure. This is a two armed, prospective, randomized, placebo-controlled, multi-centric european phase IIb trial with placebo and mirabegron distributed in a 1:1 fashion. The patients enrolled will have cardiac structural remodeling with or without symptoms of heart failure (maximum NYHA II).

Patients will be monitored for change in left ventricular mass (assessed by cardiac MRI) and/or changes in diastolic function (assessed by echocardiography) after 12 months of treatment.

Background Heart failure (HF) represents a major and growing public health burden. Patients with HF are classically divided into two groups: those with HF with preserved ejection fraction (HFpEF), and those with HF and reduced ejection fraction (HFrEF). As HF is a progressive disorder increasing with age, the proportion of these patients is rising due to the aging of the population. Beside costs, HFpEF also puts a heavy burden on the quality of life of (mostly elderly) patients, with a loss of autonomy and the dyscomfort of repeated hospitalisations. Therefore, HFpEF is a chronic, costly, debilitating disease.

A major contributor to HFpEF is myocardial remodelling, e.g. hypertrophy and fibrosis, as well as cellular functional/structural modifications leading to alteration in contractile properties and ventricular distensibility. Unfortunately, there are currently no evidence-based treatment strategies.

Study claim The proposed clinical trial will provide a proof of concept in humans for the clinical efficacy of a novel therapeutic concept: β3AR activation to attenuate/prevent cardiac remodeling. Recently, a new, specific agonist at human β3-AR (mirabegron) with higher benefit/risk balance was developed and marketed for clinical use in a non-cardiovascular disease (overactive bladder disease). The trial will test the drug repurposing of mirabegron for the prevention of cardiac remodeling leading to HFpEF.

Using pre-clinical models, the investigators demonstrated that activation of β3AR attenuates myocardial hypertrophy and fibrosis in response to neurohormonal or hemodynamic stresses, without compromising LV function. Therefore, the recent availability of this new drug offers the possibility to test the potential benefit of mirabegron (vs placebo) as add-on therapy (on top of standard care) to prevent/delay myocardial remodelling in patients at high risk of developing HFpEF.

Who can participate? Patients with structural cardiac disease with or without HF symptoms (max. NYHA 2).

What does the study involve? Patients will be requested to go 5 times to the hospital to perform cardiac MRI (3X), echocardiography (3X), exercise tolerance test (2X), Pet scanning (2X) and blood sampling (4X).

Who is the sponsor? The Université catholique de Louvain (UCL) is the academic sponsor and Prof. Jean-Luc Balligand is the principal coordinator of the study.

Who is funding the study? Beta3_LVH is an investigator-initiated project funded by a Horizon 2020 grant from the European Commission.

Inclusion Criteria:

• Age between 18 and 90 years
• Arterial hypertension on stable therapy according to current guideline algorithms (including stable medication for at least four weeks before inclusion),
• Morphological signs of structural cardiac remodelling by echocardiography, i.e. increased LV mass index (110 g/m2 or higher for female; 134 g/m2 or higher for male subjects (Devereux, Reichek 1977)) or end-diastolic wall thickness > or equal to 13 mm in at least one wall segment
• Patients may have atrial fibrillation (AF), but with well-regulated ventricular response, i.e. heart rate<100/min (RACE II - (Groenveld et al. 2013, 2013)),
• Written informed consent
• For subjects unable to read and/or write, oral informed consent observed by an independent witness is acceptable if the subject has fully understood oral information given by the Investigator. The witness should sign the consent form on behalf of the subject.

Exclusion Criteria:

• Unstable hypertension with systolic BP≥160 mm Hg and/or diastolic BP≥100 mm Hg (based on office measurement, not ambulatory measurement)
• Documented ischemic cardiac disease
• History of hospitalization for overt heart failure within last 12 months
• Patients after heart transplantation
• Genetic hypertrophic or dilated cardiomyopathy
• Dysthyroidism.
• Severe valvulopathy
• NYHA-class > II
• BMI >40 kg/m2
• EF < 50%, regardless of symptoms
• Known other cause (i.e. COPD) of respiratory dysfunction; patients under positive pressure (CPAP) treatment for sleep apnea syndrome may be included, provided they have been under regular treatment for at least one year before inclusion in the study
• eGFR < 30 ml/min (by MDRD formula)
• Abnormal liver function tests
• Type I diabetes, complicated type II diabetes
• Patients with anemia
• Patients with bladder outlet obstruction
• Patients using antimuscarinic cholinergic drugs for treatment of OAB
• Current use of digitalis, bupranolol, propranolol, nebivolol
• Patients continuously treated with Sildenafil or other PDE5 inhibitors.
• Current use of antifungal azole derivatives (fluconazole, itraconazole, miconazole, posaconazole, voriconazole)
• Current treatment with mirabegron or indication for future treatment with mirabegron due to other indications
• Contraindication for MRI
• Pregnant or nursing women
• Participation in any other interventional trial
• Fertile women (within two years of their last menstruation) without appropriate contraceptive measures (hormonal implant, injections, oral contraceptives, intrauterine devices, partner with vasectomy) while participating in the trial (participants using a hormone-based method have to be informed of possible effects from the trial medication on contraception)
• Contraindication to mirabegron (e.g. hypersensitivity) or any other components of the trial medication

Individual participant data required to reach aims in an approved proposal, after de-identification, will be made available to investigators whose proposed use of the data has been approved by the study's Executive Committee. Proposals may be submitted up to 36 months after publication of the study results and should be directed to Jean-Luc.Balligand@uclouvain.be.

up to 36 months after publication of the study results

Upon approval by the study Steering Committee of a valid proposal by requesters