Ischaemic HFrEF with LBBB — ICD, CRT-D and atrial fibrillation: case discussion

Presentation

Practice case (not a real patient). A 67-year-old man had an inferior myocardial infarction (MI) 3 years ago and coronary artery bypass grafting 2 years ago. He has heart failure with reduced ejection fraction (HFrEF) of ischaemic aetiology and New York Heart Association (NYHA) class III symptoms. After 6 months of optimal foundational medical therapy (FMT), his left ventricular ejection fraction (LVEF) is 28%. He is in sinus rhythm with left bundle branch block (LBBB) and a QRS duration of 158 ms. He has had no ventricular arrhythmia, still works part time, and is expected to survive longer than 1 year with good functional status.^[1]

Step 1 — Does he need an implantable cardioverter-defibrillator (ICD)?

Discussion:

• This is primary prevention: he has had no ventricular arrhythmia, so the secondary-prevention rows do not apply.^[1]
• 2026 European Society of Cardiology (ESC) heart failure: an ICD is recommended in symptomatic HFrEF (NYHA class II/III) of ischaemic aetiology (unless there was an MI in the prior 40 days), with LVEF ≤35% despite ≥3 months of optimal FMT, provided survival longer than 1 year with good functional status is expected, to reduce the risk of sudden death and all-cause death (Class I, Level B1); he meets every condition.^[1]
• 2022 American Heart Association/American College of Cardiology/Heart Failure Society of America (AHA/ACC/HFSA) had recommended ICD therapy for primary prevention of sudden cardiac death (SCD) to reduce total mortality in ischemic heart disease at least 40 days post-MI with LVEF ≤35% and NYHA class II or III symptoms on chronic guideline-directed medical therapy (GDMT), with reasonable expectation of meaningful survival for >1 year (COR 1, LOE A); for post-MI patients like him, the 2025 ACC/AHA ACS row for selected patients with LVEF ≤40% now applies.^[5][8]
• 2025 ACC/AHA acute coronary syndrome (ACS): an ICD is recommended in selected post-MI patients with LVEF ≤40% (Table 17) at least 40 days post MI and at least 90 days postrevascularization, to reduce death (COR 1, LOE A); his MI and his bypass surgery are years ago, and LVEF ≤30% with NYHA class III is a Table 17 category.^[8]
• The ESC 2022 chronic coronary artery disease row for this group (Class I, Level A) was replaced by the ESC 2026 row and is history.^[3][1]
• The dated NHFA/CSANZ 2018 rows agree in direction: an ICD should be considered for primary prevention in HFrEF with ischaemic heart disease and LVEF ≤35% (Strong recommendation FOR; moderate quality of evidence).^[7]

Step 2 — Does the QRS earn cardiac resynchronization therapy (CRT)?

Discussion:

• ESC 2026: CRT is recommended in symptomatic HFrEF with LVEF ≤35% despite optimal FMT, in sinus rhythm with LBBB and QRS duration ≥150 ms, to improve symptoms and reduce the risk of hospitalizations and death (Class I, Level A).^[1]
• 2022 AHA/ACC/HFSA: with LVEF ≤35%, sinus rhythm, LBBB with QRS ≥150 ms and NYHA class II, III or ambulatory IV symptoms on GDMT, CRT is indicated to reduce total mortality, reduce hospitalizations, and improve symptoms and QOL (COR 1, LOE B-R).^[5]
• 2023 Heart Rhythm Society (HRS): with LVEF ≤35%, sinus rhythm, LBBB with QRS ≥150 ms and NYHA class II-IV symptoms on GDMT, CRT with biventricular (BiV) pacing is indicated to improve symptoms and reduce morbidity and mortality (COR 1, LOE A).^[6]
• The dated NHFA/CSANZ 2018 row also recommends CRT in HFrEF with sinus rhythm, LVEF ≤35% and QRS of 150 ms or more despite optimal medical therapy (Strong recommendation FOR; high quality of evidence).^[7]

Step 3 — CRT-P or CRT-D?

Discussion:

• ESC 2021 pacing: in patients who are candidates for an ICD and have a CRT indication, implantation of a CRT with defibrillator (CRT-D) is recommended (Class I, Level A); he is both.^[2][1]
• ESC 2022: when an ICD is indicated, it is recommended to evaluate whether the patient could benefit from CRT-defibrillator (Class I, Level C).^[3]
• ESC 2021 text (no class or level given) says the addition of an ICD to CRT should be considered especially in younger patients with a good survival prognosis, ischaemic aetiology and a favourable comorbidity profile or presence of myocardial fibrosis.^[2]

Step 4 — The coronary sinus lead cannot be placed

Discussion:

• ESC 2026: no RCT with patient-centred outcomes has evaluated conduction system pacing (CSP) in HFrEF, and no recommendations can currently be made; for his HFrEF this is the later ESC position.^[1]
• ESC 2021 had said that, in CRT candidates in whom coronary sinus lead implantation is unsuccessful, His bundle pacing (HBP) should be considered as a treatment option along with other techniques such as a surgical epicardial lead (Class IIa, Level B).^[2] That is an earlier row: for HFrEF, the later ESC 2026 HF guideline makes no recommendation on CSP because no RCT with patient-centred outcomes has evaluated it.^[1]
• HRS 2023: with LVEF ≤35%, sinus rhythm, LBBB with QRS ≥150 ms and NYHA class II-IV on GDMT, CSP with HBP with LBBB correction or left bundle branch area pacing (LBBAP) is reasonable if effective CRT cannot be achieved with BiV pacing based on anatomical or functional criteria (COR 2a, LOE C-LD).^[6]
• HRS 2023 also grades crossover: in patients undergoing CRT with BiV pacing implantation via the coronary sinus (CS), crossover to CSP with HBP or LBBAP is reasonable when the CS left ventricular lead placement is unsuccessful or suboptimal (COR 2a, LOE C-LD), and crossover to surgical epicardial CRT with BiV pacing might be reasonable when the initial approach is unsuccessful or suboptimal (COR 2b, LOE C-LD).^[6]
• HRS 2023: if an HBP lead is chosen in an ICD or CRT-D, it should not be used for tachycardia detection.^[6]

Step 5 — Eighteen months later: atrial fibrillation

Practice case continued. A biventricular CRT-D was implanted. He now has permanent atrial fibrillation (AF). Despite drug rate control, device checks show 84% biventricular pacing because of conducted AF. He remains NYHA class III with LVEF 30% and an intrinsic QRS ≥130 ms, and he has had no hospitalization for HF.^[2]

• ESC 2021 had said that, in patients with HF with permanent AF who are candidates for CRT, atrioventricular junction (AVJ) ablation should be added in the case of incomplete biventricular pacing (<90–95%) due to conducted AF (Class IIa, Level B). It is an earlier row; the later ESC 2026 row on AV node ablation combined with CRT is set out below with its own conditions.^[2][1]
• 2023 ACC/AHA/ACCP/HRS AF: in AF, HF and implanted biventricular pacing therapy where an effective pacing percentage cannot be achieved with pharmacological therapy, AV nodal ablation can be beneficial to improve functional class, reduce the risk of ICD shock, and improve survival (COR 2a, LOE B-NR).^[10]
• 2022 AHA/ACC/HFSA: in AF with LVEF ≤35% on GDMT, CRT can be useful to reduce total mortality, improve symptoms and QOL, and increase LVEF, if the patient requires ventricular pacing or otherwise meets CRT criteria and AV nodal ablation or pharmacological rate control will allow near 100% ventricular pacing with CRT (COR 2a, LOE B-NR).^[5]
• The ESC 2026 HF row on AV node ablation combined with CRT to reduce symptoms, physical limitations, recurrent HF hospitalization and death (Class IIa, Level B1) is written for severely symptomatic permanent AF with poor rate control despite medical therapy and at least one HF hospitalization; he has had no HF hospitalization, so it is not the row that applies here.^[1]
• ESC 2026 lists the percentage of effective biventricular pacing (without fusion or pseudofusion) as an important focus of follow-up in AF.^[1]

Step 6 — Rehabilitation and the long term

Discussion:

• 2026 ESC cardiac rehabilitation: cardiac rehabilitation is recommended after ICD or CRT device implantation to improve physical functioning (VO₂ peak, 6-minute walk distance) (Class I, Level B1).^[11]
• ESC 2026: regular follow-up and optimization should be implemented after CRT, as CRT programming and FMT may require further optimization after implantation.^[1]
• ESC 2026: before generator replacement, a shared decision-making process between the patient and a cardiologist experienced in cardiac implantable electronic devices (CIEDs) and HF should be considered to ensure that the balance between risks and benefits still favours a CIED (Class IIa, Level C).^[1]
• ESC 2026 reminds that a considerable residual risk of SCD remains even after LVEF improvement with FMT and CRT.^[1]