Due to existing evidence eligible patients receive CRT treatment in first place

The goal of X-Change HF is to estimate the effect of biventricular stimulation in patients who need antibradycardia ventricular stimulation (more than 80%); are eligible for the exchange of an old pacemaker or implantable cardioverter defibrillator (ICD); and have ventricular dysfunction (left ventricular ejection fraction [LVEF] < 35%). All patients eligible for participation in the study will be upgraded with a cardiac resynchronization therapy (CRT)-device and receive either right ventricular or biventricular stimulation in a crossover protocol. The endpoint is functional performance measured by spiroergometry.

Inclusion Criteria:

• Implanted dual-chamber pacemaker or ICD system with replacement indication

  • Because of battery end of life

  • Because of upgrade from pacemaker to ICD system

    • predominant sinus rhythm (paroxysmal atrial fibrillation [AF] < 2 hours/day)
    • predominant ventricular stimulation (>= 80%)
    • NYHA Class II-III
    • LVEF <= 35%

Exclusion Criteria:

• NYHA Class IV

• Life expectancy of less than one year because of accompanying diseases

• Myocardial infarction less than 3 months old

• Cardiac surgery less than 3 months

  • Bypass
  • Valve surgery
  • Percutaneous transluminal coronary angioplasty (PTCA)

• Thoracotomy, for implant of an epicardial LV electrode

• Medical circumstances that make participation and compliance impossible

• Patients who are not willing or able to give written consent for their study participation

• Participation in another study

• Patients less than 18 years old

• Pregnancy