Background
The wearable cardioverter defibrillator (WCD) provides temporary protection against sudden cardiac death in patients with newly diagnosed heart failure and reduced left ventricular ejection fraction (LVEF). Since 2021, new WCD models have incorporated telemonitoring features such as heart rate, daily step count, and body position, but their prognostic value remains insufficiently studied.
Purpose
To assess whether newly available WCD-derived parameters are associated with LVEF improvement and clinical outcomes.
Methods
In this retrospective single-center study, we analyzed 242 patients who received a WCD between 2010 and 2024 (140 without and 102 with access to the new features). Clinical characteristics, biomarkers, pharmacotherapy, and WCD-derived parameters were extracted from electronic health records and the Zoll® Patient Management Network. The primary endpoint was the change in LVEF; the secondary endpoint was all-cause mortality. Multivariable linear and logistic regression analyses were conducted separately for patients with and without the new features.
Results
In the overall cohort, mean LVEF increased by 9.2 ± 10.9% (n = 242; mean age 63 ± 16 years; 75.6% male). Among patients with the new WCD features, higher daily step count and receiving all four guideline-directed heart failure therapies were independently associated with greater LVEF recovery, whereas longer upright time (reflecting sitting and immobility) was negatively associated. Logistic regression confirmed complete medical therapy as an independent predictor of LVEF improvement >5%. Heart rate, BNP, creatinine, GFR, sex, ischemic etiology, and hypertension showed no significant association with recovery. In patients without the new features, younger age, improvement in NYHA class, and preserved renal function were predictive of LVEF recovery, whereas BNP and creatinine were not. All-cause mortality occurred in both groups but was not significantly related to WCD-derived parameters.
Conclusion
In patients with new WCD features, daily step count and body position were independently associated with LVEF recovery, whereas outcomes without these features were driven by age, NYHA class, and renal function. These findings support incorporating device-derived activity metrics into prognostic stratification.
