Is an implantable cardioverter-defibrillator (AICD) still indicated for a patient with a history of Heart Failure with Reduced Ejection Fraction (HFrEF) who has since experienced an improvement in their ejection fraction (EF)?

AICD Remains Indicated for Patients with HFimpEF

Yes, implantable cardioverter-defibrillator (AICD/ICD) therapy should be continued in patients with a history of HFrEF who have experienced improvement in ejection fraction (HFimpEF), and guideline-directed medical therapy (GDMT) must be maintained to prevent relapse of left ventricular dysfunction. 1

Understanding HFimpEF Classification

The 2022 AHA/ACC/HFSA guidelines specifically created the category of "Heart Failure with Improved Ejection Fraction" (HFimpEF) to address this exact clinical scenario 1:

• HFimpEF is defined as: Previous LVEF ≤40% with a follow-up measurement of LVEF >40% 1
• Critical concept: HFimpEF is classified as a subgroup of HFrEF, not as HFpEF or a separate entity 1
• Patients with HFimpEF should continue HFrEF treatment including device therapy 1

Why Improved EF Does Not Equal Full Recovery

Improvement in LVEF does not mean full myocardial recovery or normalization of left ventricular function 1:

• Cardiac structural abnormalities persist in most patients, including LV chamber dilatation and ventricular systolic/diastolic dysfunction 1
• Changes in LVEF are not unidirectional - patients may experience improvement followed by decrease in EF depending on underlying cause, disease duration, GDMT adherence, or reexposure to cardiotoxicity 1
• EF can decrease after withdrawal of pharmacological treatment in many patients who had improved EF to normal range with GDMT 1
• Trajectory of LVEF over time is important, and significant reduction in LVEF is a poor prognostic factor 1

Guideline Recommendation for GDMT Continuation

Class I, Level of Evidence B-R recommendation: In patients with HFimpEF after treatment, GDMT should be continued to prevent relapse of HF and left ventricular dysfunction, even in patients who may become asymptomatic 1

This Class I recommendation explicitly includes:

• Continuation of all HFrEF medications (ARNi/ACEi/ARB, beta-blockers, MRAs, SGLT2i) 1
• By extension, device therapies indicated for HFrEF should also be maintained 1

ICD Therapy Considerations in the Contemporary Era

While the landmark ICD trials preceded modern 4-pillar GDMT, the evidence supports continued ICD benefit 2, 3, 4:

• ICD provides high economic value in primary prevention of sudden cardiac death when the patient's risk of death from ventricular arrhythmia is deemed high and risk of nonarrhythmic death is low based on comorbidities and functional status 1
• Contemporary GDMT (including ARNI, SGLT2i) reduces sudden cardiac death risk, but does not eliminate it 2, 3, 4
• The risk of sudden cardiac death in patients with improved EF who discontinue ICD therapy remains poorly characterized 5

Practical Clinical Algorithm

At time of ICD generator replacement or reassessment:

1. Confirm the patient has HFimpEF (previous LVEF ≤40%, now >40%) 1

2. Verify optimal GDMT is maintained:

   • ARNi (or ACEi/ARB if ARNi not feasible) 1
   • Beta-blocker (bisoprolol, carvedilol, or metoprolol succinate) 1
   • MRA (spironolactone or eplerenone) 1
   • SGLT2i 1

3. Continue ICD therapy unless:

   • Life expectancy <1 year with poor functional status 1
   • High burden of comorbidities suggesting nonarrhythmic death more likely than arrhythmic death 1
   • Patient goals of care have changed 1

4. Monitor LVEF trajectory - recognize that EF may decrease again, particularly if GDMT is interrupted 1

Critical Pitfalls to Avoid

• Do not reclassify HFimpEF patients as HFpEF even if subsequent LVEF reaches >50% - they remain in the HFrEF treatment paradigm 1
• Do not discontinue GDMT based on improved EF, as this frequently leads to EF decline 1
• Do not assume structural heart disease has resolved - persistent abnormalities remain despite improved EF 1
• Carefully evaluate before generator replacement as management goals and patient needs may have changed, but default should be continuation unless specific contraindications exist 1