Today patients with a Cardiac Resynchronization Therapy (CRT) indication usually receive 2 ventricular leads, right ventricular (RV) apex and left ventricular (LV) (postero-) lateral, gaining a responder rate of approximately 70%. However, the physiological agitation of the left ventricle takes place over two pathways. Therefore single point stimulation might be insufficient for a dilated, insufficiently and asynchronously contracting left ventricle, resulting in either insufficient or no response to the therapy.

In the "CRT ICD Dual LV" study the patients receive a second LV lead in an anterior vein. When this lead is placed, temporary dual LV stimulation is started. To assess the effectivity of the dual LV lead stimulation intraoperatively a LV dp/dt-pressure measurement is taken. If there is an increase in LV dp/dt, the patients will be stimulated with both leads permanently. If not they will be stimulated conventionally.

The patients participating in this study are monitored for 12 months after implantation.

Inclusion Criteria:

• EF less than 35 percent
• CAD or dilatative Cardiomyopathy
• Sinus rhythm
• NYHA III or IV, stable recompensated
• QRS more than 120ms
• LBBB
• Patient signed Consent Form
• Age more than 18 and less than 80 y

Exclusion Criteria:

• permanent atrial Fibrillation
• permanent AV-Block II or III
• Tricuspidal- and or artificial aortic valve
• Indication for ACB or ACB less than 3 months ago
• myocardial infarction less than 3 months
• hypertrophic obstructive Cardiomyopathy; constrictive Pericarditis
• heartfailure with iv catecholamine therapy
• Manifested, uncontrolled, Hypo- oder Hyperthyreosis
• Severe renal insufficiency with Creatinine more than 2,5 mg per dL
• patients, who did not sign the consent form
• General medical conditions, which restrict the patient compliance
• Participation in another study
• life expectancy less than 1 y
• Age less than 18 y or more than 80y
• Pregnant women or Women of childbearing age