Risk Stratification for Implantable Cardioverter Defibrillator Therapy: The Role of the Wearable Cardioverter-Defibrillator
The following are 10 points to remember from this clinical update on the wearable cardioverter-defibrillator (WCD):
1. The WCD vest holds two posterior defibrillation electrodes, one apical defibrillation electrode, and four small nonadhesive electrodes for electrocardiographic monitoring.
2. The monitor/defibrillator unit weighs approximately 1 pound, and is carried in a belt holster.
3. If the patient is not capable of pressing a response button upon triggering of vibratory and aural alarms, a shock is delivered 45-55 seconds after onset of ventricular tachycardia/ventricular fibrillation, and up to four additional shocks are delivered if the arrhythmia persists.
4. A WCD can be useful to prevent sudden cardiac death (SCD) in patients with an acute myocardial infarction and poor left ventricular function during the 40 days before an implantable cardioverter-defibrillator (ICD) can be implanted.
5. Current guidelines recommend waiting 90 days before implanting an ICD post-revascularization in patients with an ejection fraction (EF) <35%, and a WCD can be used to prevent SCD during this waiting period.
6. The WCD also is useful in patients with new-onset heart failure and EF ≤35% during the 3-month waiting period before an ICD can be implanted if still indicated.
7. Patients with a myocarditis or cardiomyopathy that could be temporary, such as takotsubo cardiomyopathy or post-partum cardiomyopathy, can benefit from a WCD until recovery of left ventricular function.
8. The WCD can be used in high-risk patients with syncope of unclear etiology when there is not yet adequate evidence that an ICD is appropriate.
9. The WCD can be used during temporary ICD removal for device infection.
10. Limitations of the WCD include dependence on patient compliance and the lack of antibradycardia pacing.
Keywords: Myocardial Infarction, Tachycardia, Ventricular, Takotsubo Cardiomyopathy, Ventricular Function, Left, Ventricular Fibrillation, Electric Countershock, Heart Failure, Syncope, Myocarditis, Death, Sudden, Cardiac, Defibrillators, Implantable
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