Indications for referral for CRT for patients in sinus rhythm with LVEF ≤35%

CRT: cardiac resynchronization therapy; LVEF: left ventricular ejection fraction; LBBB: left bundle branch block QRS pattern on ECG; non-LBBB: any QRS pattern other than LBBB; NYHA: New York Heart Association.
* Most patients with an LVEF ≤35% with an indication for CRT also have an indication for an implantable cardioverter-defibrillator (ICD). Evaluation for CRT includes choosing between a pacemaker (CRT-P) and a combined CRT-ICD (CRT-D).