What are the guidelines for using a wearable cardioverter-defibrillator (WCD) in a patient with a left ventricular ejection fraction (LVEF) of 25-30%?

Guidelines for Life Vest Use in Patients with EF 25-30%

A wearable cardioverter-defibrillator (WCD) may be reasonable for patients with LVEF 25-30% who are at increased risk of sudden cardiac death but are not eligible for an immediate implantable cardioverter-defibrillator (ICD). 1

Primary Indications for WCD Use

The decision to prescribe a WCD for a patient with LVEF 25-30% should follow this algorithm:

1. Determine if patient meets criteria for permanent ICD implantation

   • If LVEF ≤30% with NYHA class I symptoms and ≥40 days post-MI, permanent ICD is indicated 1
   • If LVEF ≤35% with NYHA class II or III symptoms and ≥40 days post-MI, permanent ICD is indicated 1

2. If permanent ICD is indicated but cannot be implanted immediately, consider WCD for:

   • Patients awaiting cardiac transplant 1
   • Patients within 40 days after myocardial infarction 1
   • Patients with newly diagnosed non-ischemic cardiomyopathy 1
   • Patients within 90 days after revascularization 1
   • Patients with myocarditis or secondary cardiomyopathy 1
   • Patients with systemic infection 1
   • Patients who had ICD removal due to infection 1

Clinical Considerations

• Timing of reassessment: Patients with reduced LVEF should be reassessed after 3 months of optimal medical therapy to determine if LVEF has improved beyond the threshold for ICD implantation 1

• Compliance requirements: For effective protection, patients should wear the WCD for at least 20 hours per day. Real-world data shows average wear time of 21.2 ± 4.3 hours per day 2

• Expected outcomes: In patients using WCD, approximately 2.2% receive appropriate shocks for life-threatening arrhythmias, while only 0.5% experience inappropriate shocks 2

• Duration of therapy: The average duration of WCD use is typically 2-3 months (58-71 days), depending on the underlying condition and regional practice patterns 2

Special Considerations

• Age factor: Younger patients tend to have lower compliance with WCD wear time 2, requiring additional education and support

• Right ventricular function: While LVEF is the primary criterion for device therapy decisions, right ventricular dysfunction may be present in up to 56% of patients with preserved LVEF (≥35%) 3. This should be considered in borderline cases.

• Improvement in LVEF: Approximately 46% of patients prescribed a WCD will show improvement in LVEF to >35% during follow-up 2, potentially avoiding the need for permanent ICD implantation

Pitfalls to Avoid

1. Premature ICD implantation: Avoid permanent ICD implantation within 40 days after MI, as this has not been shown to improve survival 1

2. Delayed protection: Don't leave high-risk patients unprotected while waiting for LVEF improvement or ICD implantation

3. Inadequate patient education: Failure to properly instruct patients on WCD use can lead to poor compliance and reduced protection

4. Overlooking guideline-directed medical therapy: Ensure patients receive optimal heart failure medications which may improve LVEF and reduce arrhythmic risk

5. Neglecting reassessment: Always reassess LVEF after a period of medical therapy before proceeding to permanent ICD implantation

The WCD serves as a valuable bridge therapy for patients with severely reduced LVEF who are at risk for sudden cardiac death but are not immediate candidates for permanent ICD implantation.