Quartet 1457Q Left Ventricular (LV) Lead Investigational Device Exemption (IDE) Study

Inclusion Criteria

• Meets current St. Jude Medical clinical indication for implantation of a cardiac resynchronization therapy system:

" to provide a reduction of the symptoms of moderate to severe heart failure (New York Heart Association Functional Class III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy and have a left ventricular ejection fraction ≤ 35% and a prolonged QRS duration, OR " to maintain synchrony of the left and right ventricles in patients who have undergone an Atrio Ventricular nodal ablation for chronic (permanent) atrial fibrillation and have New York Heart Association Functional Class II or III heart failure.

• Is receiving a new market-approved St. Jude Medical quadripolar cardiac resynchronization therapy system implant with the Quartet 1457Q LV lead.
• Have the ability to provide informed consent for study participation and is willing and able to comply with the prescribed follow-up tests and schedule of evaluations.
• Are 18 years or above, or of legal age to give informed consent specific to state and national law.

Exclusion Criteria

• Had a previous unsuccessful commercial or non-Quartet 1457Q LV lead implant attempt
• Have a hypersensitivity to a single 1.0mg dose of dexamethasone sodium phosphate
• Patient is currently participating or plans to participate in a potentially confounding drug or device trial during the course of this study. Co-enrollment in other studies may be allowed if pre-approval is granted from the study manager.
• Are pregnant or planning pregnancy in the next 6 months
• Have a life expectancy of less than 24 months due to any condition