CRT can be useful for patients who have LVEF of 35% or less, sinus rhythm, LBBB with a QRS duration of 120 to 149 ms, and NYHA class II, III, or ambulatory IV symptoms on GDMT (250 254,258). (Level of Evidence: B) 3. CRT can be useful in patients with AF and LVEF of 35% or less on GDMT if a) the patient requires ventricular pacing or otherwise meets CRT criteria and b) atrioventricular nodal ablation or pharmacological rate control will allow near 100% ventricular pacing with CRT (259 264). (Level of Evidence: B) 4. CRT can be useful for patients on GDMT who have LVEF of 35% or less and are undergoing placement of a new or re- placement device implantation with anticipated requirement for signi cant (>40%) ventricular pacing (261,265 267). (Level of Evidence: C) Table 13. Medical Therapy for Stage C HFrEF: Magnitude of Benefit Demonstrated in RCTs GDMT RR Reduction in Mortality (%) NNT for Mortality Reduction (Standardized to 36 mo) RR Reduction in HF Hospitalizations (%) ACE inhibitor or ARB Aldosterone antagonist ACE indicates angiotensin-converting enzyme; ARB, angiotensin-receptor blocker; GDMT, guideline-directed medical therapy; HF, heart failure; HFrEF, heart failure with reduced ejection fraction; NNT, number needed to treat; RCTs, randomized controlled trials; and RR, relative risk. Adapted with permission from Fonarow et al. (201). yCounseling should be speci c to each individual patient and should include documentation of a discussion about the potential for sudden death and nonsudden death from HF or noncardiac conditions. Information should be provided about the ef cacy, safety, and potential complications of an ICD and the potential for de - brillation to be inactivated if desired in the future, notably when a patient is approaching end of life. 