CRT may be considered for patients in sinus rhythm with NYHA class II, NYHA class III, or ambulatory NYHA class IV heart failure, a LVEF ≤ 35%, and QRS duration > 150 msec not because of LBBB conduction (Recommendation Weak, Quality Low).

Values and Preferences This recommendation places great value on the inclusion criteria of the landmark trials, the characteristics of the patients enrolled, and the quality of this evidence. This recommendation also places greater weight on QRS duration as a determinant of CRT response.

Practical Tip There is no clear evidence of benefit with CRT among patients with QRS durations < 150 ms because of non-LBBB conduction.