Wearable cardioverter defibrillator shortens the length of stay: a single center real-world experience
Authors: Cardelli L S , Casella G , Roubille F , Pasquie J L , Leclercq F 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): ZOLL France supported with an unrestricted grant.

Background
The wearable cardioverter defibrillator (WCD) has been proven to have efficacy in treating sudden cardiac death (SCD) in patients soon after acute myocardial infarction (AMI) and left ventricular ejection fraction (LVEF) ≤35%. However, data regarding hospitalization rate and length of stay among these patients have not yet been evaluated.

Purpose
WCD can shorten hospital stays (total length, time in intensive care unit (ICU) and in cardiac intensive care unit (CICU)) of patients post-AMI, with severe reduced LVEF.

Methods
We performed a single center, retrospective observational study of patients prescribed WCD upon hospital discharge, from June 2016 to June 2022. We selected patients referred for management of SCD, post-AMI, with age over 18 years and LVEF ≤35%. Patients who already had ICD or CRT-D (or who had previously received it) were excluded from the analysis. Patients with the same characteristics, and who were discharged from the hospital without WCD or ICD served as a control group. Clinical characteristics were obtained from hospital electronic and WCD specific database. The clinical characteristics and length of index hospitalization of two groups were compared. An initial propensity score analysis was performed, then a weighted regression models for total hospitalization, days in ICU, and days in CICU were conducted.

Results
101 patients in the WCD group and 29 in the control group were enrolled in the analysis (Figure 1). The two groups showed similar clinical characteristics (Table 1), even if patients in the WCD group had lower LVEF (p &lt;0.001), more cardiogenic shocks (p = 0.045) and higher NT-proBNP values (p = 0.033). After a propensity score analysis and a weighted regression model, LVEF emerged as independent variable for WCD use (odds ratio (OR) 0.755, confidence interval (CI) 95% 0.654 – 0.872, p &lt;0.001). Left ventricular thrombosis also affected the use of WCD (OR 5.574, CI 95% 1.139 – 27.267, p = 0.0339). In a weighted regression model, WCD significantly influenced the days spent in CICU (p&lt;0.001), and those in ICU even without statistical significance (p = 0.251). Even after excluding all patients undergoing extracorporeal membrane oxygenation (ECMO) or heart transplantation, WCD reduced days spent in CICU (p&lt;0.001). Furthermore, when excluding from the analysis all patients with very long hospitalizations (&gt; 30 days), WCD patients showed significantly shorter total hospitalization (p=0.005) and days spent in CICU (p&lt;0.001), compared with control group.

Conclusions
At the propensity score analysis, WCD reduce CICU length of stay for patients post-AMI with LVEF ≤35%. The association between WCD use and hospitalization is more relevant for days spent in CICU, but there is also a positive trend for the days spent in ICU. The study has the limitation of a retrospective analysis and can only serve as hypothesis-generating research, which will be verified with further randomized clinical trial.