Heart failure is a progressive disease that decreases the pumping action of the heart. This may cause a backup of fluid in the heart and may result in heart beat changes. When there are changes in the heart beat sometimes an implantable heart device is used to control the rate and rhythm of the heart beat. In certain heart failure cases, when the two lower chambers of the heart no longer beat in a coordinated manner, cardiac resynchronization therapy may be prescribed.

People who have a dangerously fast heart beat, or whose heart is at risk of stopping beating, may be in need of an electronic device called an implantable cardioverter defibrillator (ICD).

Atrial tachyarrhythmia (AT) is the name for rapid beats in the upper chambers of the heart. People with AT may experience symptoms such as heart palpitations (a racing or pounding feeling in the chest), shortness of breath, dizziness, fatigue or weakness.

The purpose of this study is to study an investigational implantable device containing Cardiac Resynchronization Therapy (CRT) and Implantable Cardioverter Defibrillator (ICD) therapies (CRT+ICD device) in subjects who are at significant risk of developing atrial tachyarrhythmias.

Inclusion Criteria:

• Subjects who require the implantation of an Implantable Cardioverter Defibrillator
• Subjects who have heart failure that severely limits daily activities (NYHA Class III) or Subjects who have severe heart failure and should always be resting (NYHA Class IV)
• Subjects with reduced heart pumping function (left ventricular ejection fraction ≤ 35%)

Exclusion Criteria:

• Subjects who have constant atrial fibrillation (top chambers of the heart beat too fast continuously)
• Subjects who are post-heart transplant