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4. Referral for ICD and CRT

When to refer for ICD/CRT in the current era of medical therapy for HFrEF

The decision regarding when and if an ICD should be implanted must include evaluation of the short- and long term risks of sudden death due to a ventricular arrhythmia and death from nonarrhythmic causes. This is often a complex assessment and must integrate many factors including the presence of ischemic heart disease, burden of scar, frailty, advancing dementia, comorbidities, and adequacy of background medical therapy. In addition to ICD considerations, CRT further improves mortality and reduces HHF in patients with HFrEF and dyssynchrony, particularly those with QRS 150 ms.[1]

Most trials that have shown a mortality reduction for primary prevention ICD implantation or CRT were conducted in an era when conventional HFrEF therapy included β-blockers, RASi with ACEIs and ARBs, and MRAs. In the past decade, HFrEF therapies such as sacubitril-valsartan,[5] ivabradine,[60] SGLT2 inhibitor,[40],[41] and vericiguat[71] have also shown a reduction in CV death and worsening HF events in patients with HFrEF. In part, this might be because of the beneficial effects of these agents on ventricular function. For example, in the echocardiography substudy of the SHIFT trial (discussed previously), among the 411 patients who had paired baseline and 8-month follow-up echocardiography data, there was an increase in LVEF of 2.4% (SD, 7.7) in ivabradine-treated patients compared with a decrease of 0.1% (SD, 8.0%) in the placebo group (P < 0.001).[80] Similarly, patients with NYHA II-IV symptoms and LVEF < 40% who were switched from an ACEI/ARB to an ARNI in the open-label, single-arm Prospective Study of Biomarkers, Symptom Improvement, and Ventricular Remodeling During Sacubitril/Valsartan Therapy for Heart Failure (PROVE-HF) study, there was an increase in LVEF by 4.9% (range, 4.5%-5.3%) at 6 months and 8.8% (range, 8.3%-9.3%) at 12 months.[81] In a meta-analysis of 9 studies including 707 patients with HFrEF, the LVEF increased by 4.9% (range, 4.13%-5.65%) after patients were switched to treatment with an ARNI.[82] Because of the demonstrated benefits of current HFrEF therapies to improve LVEF over time, it seems prudent to ensure that GDMT has been optimized before implanting primary prevention ICDs and CRT. However, it must be emphasized that there are no randomized controlled trial data on the risk/benefit of ICD implantation and CRT before vs after the initiation of newer HFrEF therapies. Every attempt should be made to initiate and titrate GDMT as quickly as feasible to avoid delays in referring suitable patients with persistently reduced LVEF for device therapy.


21. We recommend that after a diagnosis of HFrEF, standard medical therapy should be initiated and titrated to target or maximally tolerated doses with a repeat assessment of LVEF before referral for ICD or CRT (Strong Recommendation; Moderate-Quality Evidence).

Practical Tip

Reassessment of ejection fraction should be performed 3 months after the achievement of target or maximally tolerated doses of GDMT.

An assessment of arrhythmic and non-arrhythmic sudden cardiac death (SCD) risk should be performed to estimate the risk/benefit of ICD implantation or CRT.

Specific HF therapies might contribute to improvements in LVEF and should be considered before referral for ICD implantation or CRT:

  • For eligible patients, switching to ARNI therapy should be considered before referral for ICD or CRT.
  • Additional use of ivabradine, where otherwise indicated after β-blocker optimization, should be considered before referral for ICD implantation or CRT.

Referral for ICD implantation or CRT should not be unduly delayed if timely titration of pharmacologic therapies is infeasible or impractical.


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