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According to Zoll, the WEARIT-II registry includes more than 2,000 patients prescribed the LifeVest wearable defibrillator. Advice module 734 can include a Shock Advisory Algorithm, implement decision rules, and so on. The advice can be to shock, to not shock, to administer other forms of therapy, and so on. If the advice is to shock, some external defibrillator embodiments merely report that to the user, and prompt them to do it. Other embodiments further execute the advice, by administering the shock.
The only randomised controlled trial investigating its use to date is the VEST trial 6 It failed to show a significant reduction ZOLL LifeVest Wearable Defibrillator in arrhythmic death in patients with severely reduced EF during the early post-myocardial infarction phase with use of the WCD.



39. Unknown Cardiac Prognosis  Use of WCDs may be reasonable when there is concern about a heightened risk of SCD that may resolve over time or treatment of left ventricular dysfunction, for example, in ischemic heart disease with recent revascularization, newly diagnosed nonischemic dilated cardiomyopathy in a patient starting guideline-directed medical therapy, or secondary cardiomyopathy (tachycardia mediated, thyroid mediated, etc) in which the underlying cause is potentially treatable (Class IIb; Level of Evidence C) 39 Piccini JP, Allen LA, Kudenchuk PJ, Page RL, Patel MR, Turakhia MP. Wearable Cardioverter-Defibrillator Therapy for the Prevention of Sudden Cardiac Death.
For example, patients who have had large myocardial infarctions or undergone coronary revascularization with decreased left ventricular function (LVEF ++<++ 30%) may be candidates for ICD implantation if their ventricular function does not improve after 1 or 3 months, respectively (MADIT-2 criteria).

If the first set of defibrillation waveforms delivered across the first set of vectors fail to establish a regular heart rhythm in the patient, the defibrillator circuit has the capability to deliver a second set of defibrillation waveforms across the second set of vectors.
44. Recommendation  Use of WCDs is reasonable as a bridge to more definitive therapy such as cardiac transplantation (Class IIa; Level of Evidence C) 44 Piccini JP, Allen LA, Kudenchuk PJ, Page RL, Patel MR, Turakhia MP. Wearable Cardioverter-Defibrillator Therapy for the Prevention of Sudden Cardiac Death.

However, in an as-treated analysis, a significantly lower percentage of patients died when they were wearing the wearable cardioverter-defibrillator than when they were not, a finding that remained significant even after the most conservative correction for multiple comparisons.
27. Clinical Experience With WCDs  Newly diagnosed cardiomyopathy, NYHA class IV heart failure, and those for transplantation  42% experienced recovery and did not develop an indication for permanent ICD  None of the patients had SCD or required WCD therapy  Event rates lower in patients with newly diagnosed cardiomyopathy (<1%)  Event rates are also lower in patients with recent revascularization  Although overall event rates are lower in patients with newly diagnosed cardiomyopathy or recent coronary revascularization, retrospective observational data suggest that the WCD may confer a survival benefit 27 Piccini JP, Allen LA, Kudenchuk PJ, Page RL, Patel MR, Turakhia MP. Wearable Cardioverter-Defibrillator Therapy for the Prevention of Sudden Cardiac Death.