Abstract Body (Do not enter title and authors here): Background and Aims
In patients with non-ischemic cardiomyopathy (NICM), conditions such as peripartum cardiomyopathy or myocarditis may resolve, and an increase in left ventricular ejection fraction (LVEF) may occur within the first months of initiating guideline-directed medical therapy before considering an implantable cardioverter defibrillator (ICD). However, patients are at increased risk for sudden cardiac death (SCD) during this period, and a wearable cardioverter defibrillator (WCD) may help mitigate this transient risk. In this meta-analysis, we sought to assess the risk for appropriate shocks delivered by the WCD in patients with NICM in this vulnerable period.

Methods
A systematic literature search was conducted in Medline, Embase, and Cochrane Library to identify studies reporting the use of WCD in patients with newly diagnosed NICM before April 2024. Two independent reviewers selected studies based on predefined inclusion and exclusion criteria. The study types considered included randomized and non-randomized controlled trials, prospective and retrospective cohort studies, registry data, and case series. Publications in languages other than English, German, or French were excluded. Studies with mixed populations (including patients with ischemic heart disease) were included if separate results were reported for each indication. Data on appropriate shocks, inappropriate shocks, WCD wear time, final device implantation, and deaths were extracted. Mean incidence rates for different outcomes were calculated for each subtype of NICM.

Results
Forty-four studies were included. The mean incidence rate (per 1,000 patients) for appropriate shocks was 12 in dilated cardiomyopathy, 16 in myocarditis, 43 in peripartum cardiomyopathy, 19 in Takotsubo syndrome, and 13 in other genetic/congenital heart conditions. Inappropriate shocks were rare (<1% of patients). Finally, 1277 patients (35%) received an ICD across all studies.

Conclusion
Patients with NICM face a significant risk of SCD during the waiting period before deciding if patient qualifies for an ICD implantation. Additional efforts are needed to refine identification methods and enhance strategies to manage at-risk patients during this critical period.