The CARE-HF trial evaluates the effects of Cardiac Resynchronization (CR) therapy on the mortality and morbidity of patients with heart failure due to left ventricular systolic dysfunction already receiving diuretics and optimal medical therapy.

813 patients enrolled 82 centers in 12 countries (Austria, Belgium, Denmark, Finland, France, Germany, Italy, Netherlands, Spain, Sweden, Switzerland, and UK)

Inclusion Criteria:

• Heart failure for at least 6 weeks requiring loop diuretics
• Currently in NYHA class III/IV
• A high standard of pharmacological therapy
• LV systolic dysfunction and dilation (EF <=35%; EDD >30mm/height in metres)
• QRS >=120 ms Dyssynchrony confirmed by echo if QRS 120-149 ms (Aortic pre-ejection delay >140ms, Interventricular mechanical delay >40 ms, Delayed activation of postero-lateral LV wall)

Exclusion Criteria:

• Age < 18 years old or age < legal age defined in the country in case different
• Chronic atrial fibrillation within 6 weeks prior to randomization;
• Impairment of left ventricular function not related to left ventricular systolic function
• Potentially reversible forms of cardiomyopathy:
• Cardiac surgery, percutaneous coronary intervention, cardiomyoplasty, myocardial infarction,unstable severe angina or stroke within 6 weeks before randomization
• A conventional indication for bradyarrhythmia pacing exists;
• A conventional indication for an ICD exists
• A pacemaker or ICD has already been implanted;
• In-Patients requiring continuous intravenous therapy for Heart Failure;
• Life expectancy < 1 year for disease unrelated to Heart Failure;
• Pregnancy or childbearing potential and not on reliable contraceptive;
• Mechanical tricuspid valve;
• Anticipated compliance problem or participation in another trial;