Systematic Withdrawal of Neurohumoral Blocker Therapy in Optimally Responding CRT Patients

Inclusion Criteria: * ≥18 years * CRT implantation * based on class I recommendations of ESC (European society of CArdiology) guidelines: * Left bundle branch block (LBBB) with QRS duration \>150 ms and left ventricular ejection fraction (LVEF) ≤35% who remained NYHA functional class II, III and ambulatory IV despite adequate medical treatment * LBBB with QRS duration 120-150 ms and LVEF ≤ 35% who remain in NYHA functional class II, III and ambulatory IV despite adequate medical treatment * At the moment of inclusion: ≥ 6 months after implantation * At the moment of inclusion: normalised LVEF (≥ 50%), LVIDD/BSA (left ventricular internal diastolic diameter indexed to body surface area) ≤3.2 cm/m²(woman) en ≤3.1 cm/m² (men) or LVDV/BSA (left ventricular diastolic volume indexed to body surface area) ≤75 ml/m² (women) or ≤75 ml/m² (men) * euvolemic clinical state and functioning in NYHA class I Exclusion Criteria: * contraindication for withdrawal of ACE-I/ARB such as diabetic nephropathy and proteinuria \> 1g / 24 h * severe ventricular arrythmia (sustained VT or ventricular fibrillation) occuring at the time LV function was normalized * ischemic cardiomyopathy with evidence of scarring (scarring on MRI or severe hypokinesia/akinesia in \>1 LV wall segment on echocardiography) * known severe coronary atherosclerosis (stenosis ≥ 80%)