Strategic Management to Optimize Response To Cardiac Resynchronization Therapy


The primary objective is to evaluate the benefit of the SmartDelay™ algorithm in patients with a prolonged RV-LV interval.


  • Subject must be indicated to receive a de novo quadripolar Boston Scientific Cardiac Resynchronization Therapy Defibrillator (CRT-D) in conjunction with an ACUITY X4 LV lead. This includes subjects who are indicated to receive an upgrade to a BSC X4 CRT-D from a previously implanted device.
  • In order to achieve a homogenous population for the study, qualifying subjects are those with heart failure who meet BSC US indications for use defined as those subjects who receive stable optimal pharmacologic therapy (OPT) for heart failure and who meet any one of the following classifications:
    • Moderate to severe heart failure (NYHA Class III-IV) with EF ≤ 35% and QRS duration ≥ 120 ms
    • Left bundle branch block (LBBB) with QRS duration ≥ 130 ms, EF ≤ 30%, and mild (NYHA Class II) ischemic or nonischemic heart failure or asymptomatic (NYHA Class I) ischemic heart failure