Comparison of Right Ventricular Septal and Right Ventricular Apical Pacing in Patients Receiving a CRT-D Device

Inclusion Criteria: * Accepted CRT indication according to ESC with 1. Documented LVEF \</= 35% in last 3 months 2. Documented LVEDD ≥ 55 mm or LVEDD \> 30 mm/m2, or LVEDD \>30 mm/m (height) in last 3 months 3. QRS ≥120 ms documented on ECG recording during hospitalisation 4. NYHA Class III or ambulatory class IV stable for the last month previous enrolment * Or the previous criteria 1 and 2 and a transient episode in NYHA class III or IV with prior HF hospitalization or intravenous decongestive therapy (IV diuretics, IV neseritide or IV inotropes) in an "out-patient" setting within the year previous enrolment and stabilization to NYHA class II for the last month with a QRS ≥150 ms documented on ECG recording during hospitalisation * ICD indication (class I or II A) * Optimal and stable medication for at least one month (except for diuretics stable for minimum 1 week) based on ESC guidelines before the enrolment * Chronic heart failure (\> 3 months) stable for the last month previous enrolment * Stable sinus rhythm at the enrolment * Willing and capable of providing informed consent Exclusion Criteria * Defibrillation testing not planned during the implant procedure due to a poor haemodynamic or clinical status or other reasons * Have persistent atrial fibrillation (AF) or atrial flutter (i.e, can be terminated with medical intervention, but does not terminate spontaneously) within 1 month prior inclusion * Documented AF within 1 month prior enrolment * Life expectancy \< 12 months or expected to undergo heart transplant within the next 12 months * Uncontrolled blood pressure (Systolic BP \> 160 mmHg or Diastolic BP \> 85 mmHg) * Hospitalization for HF or intravenous inotropic drug treatment within 1 month prior enrolment * Cardiac surgery, per cutaneous transluminal angioplasty (PTCA), myocardial infarction (MI), unstable or severe angina or stroke during last 3 months prior enrolment * Previously implanted pacemaker or ICD * Uncorrected primary valvular disease * Prosthetic tricuspid valve * Nursing women or of childbearing potential who are, or might be pregnant at the time of the study * Enrolled in any on-going study (including pharmacologic trial).