• Comparison of change in Left Ventricular Ejection Fraction from baseline to 2 years. [ Time Frame: At 2-year follow-up ] [ Designated as safety issue: No ]
  

• Incidence of atrial tachyarrhythmia recorded by the pacemakers [ Time Frame: At 2-year follow-up; and at 5-year follow-up (study extension) ] [ Designated as safety issue: No ]
  
• Worsening of heart failure [ Time Frame: At 2-year follow-up; and at 5-year follow-up (study extension) ] [ Designated as safety issue: No ]

  Worsening of heart failure can be defined as:

  1. Heart failure-related hospitalization requiring intravenous heart failure therapy, or
  2. Emergency department visit for heart failure requiring intravenous heart failure therapy, or
  3. Any other visit in which the patient presents with signs or symptoms consistent with heart failure or heart failure exacerbation or marked decline in ejection fraction <35%, and intravenous heart failure therapy is required or titrate therapy.
  4. CRT-P or CRT-D upgrade.
  
  
• All cause mortality [ Time Frame: At 2-year follow-up; and at 5-year follow-up (study extension) ] [ Designated as safety issue: No ]
  
• Incidence of stroke [ Time Frame: At 2-year follow-up ] [ Designated as safety issue: No ]
  
• N-Terminal Brain Natriuretic Peptide (NT-proBNP) levels [ Time Frame: At 2-year follow-up ] [ Designated as safety issue: No ]
  
• Echocardiographic measures of left ventricular dyssynchrony [ Time Frame: At 2-year follow-up ] [ Designated as safety issue: No ]
  
• 6 minute Hall-Walk distance [ Time Frame: At 2-year follow-up ] [ Designated as safety issue: No ]
  

There is an increasing amount of evidence to suggest that other positions in the heart may be more effective than the conventional Right Ventricular Apex (RVA) position for restoring good heart function. The best site to place a lead has not yet been proven.

This is a study comparing the long term clinical effects of two different lead positions. The measurements taken to assess the clinical effects include:

• the effectiveness of the heart's pumping action (as measured by ultrasound scans)
• measurements of how far patients can walk in 6 minutes
• analysis of blood samples
• collection of information from the pacemaker about heart rhythm problems

Half of the patients in the study will receive conventional leads placed in the more common RVA position in the heart. The other half will receive a relatively new type of lead placed in what is called the Right Ventricular High Septal (RVHS) position.

In order to fairly compare the outcomes of these two different lead positions this study has been designed as a 'randomized', 'blind' trial. This means that the group which patients will be entered into will be chosen at random and patients will not be told which group they are in.

Patients will each have an equal (50:50) chance of being in either group. By carefully comparing the clinical differences between the two groups of patients, the study aims to prove whether or not there are additional benefits for patients when the RVHS lead position is used.

All leads used in the study have been shown to be safe for patients and are available commercially for implantation. All of the implanting doctors involved in the study are experienced at implanting the pacemakers and leads that will be used in this study.