Wearable Cardiac Vest for HFrEF: EF Thresholds

Definition and Classification of HFrEF

The American Heart Association, American College of Cardiology, and Heart Failure Society of America define HFrEF as heart failure with a left ventricular ejection fraction (LVEF) ≤40% 2, 3
The American College of Cardiology classifies patients with LVEF 41-49% as having HF with mildly reduced EF (HFmrEF) 2, 4
The American College of Cardiology classifies patients with LVEF ≥50% as having HF with preserved EF (HFpEF) 2, 4

The European Society of Cardiology recommends a wearable cardioverter-defibrillator for patients with recent MI and LVEF ≤35%, with a Class IIb, Level of Evidence C classification 1
The American College of Cardiology suggests that wearable cardioverter-defibrillators are primarily considered for patients with recent MI and LVEF ≤35% 1

The American College of Cardiology recommends permanent ICDs for primary prevention in HFrEF patients with LVEF ≤35% despite >3 months of optimal medical therapy 1
The American College of Cardiology recommends permanent ICDs for primary prevention in HFrEF patients with LVEF ≤30% for NYHA class I patients, with an ACC/AHA Class IB recommendation 1

The American College of Cardiology notes that wearable cardioverter-defibrillators are typically used as a bridge therapy during the waiting period before permanent ICD implantation is considered 1
The American College of Cardiology recommends against ICD implantation within 40 days after MI due to lack of early benefit shown in clinical trials 1
The American College of Cardiology suggests that the wearable vest is particularly considered during this 40-day waiting period after MI when patients are at high risk but not yet eligible for permanent ICD 1