The impact of inappropriate shocks in implantable cardioverter-defibrillators in contemporary clinical practice

Background and purpose: Implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds) are effective in preventing sudden cardiac death. However, inappropriate shocks (Inap-S) may impair quality of life and have been associated with adverse clinical outcomes. This study evaluated the incidence, predictors, and prognostic impact of Inap-S in contemporary clinical practice. Methods: This retrospective observational study identified 264 patients who underwent ICD or CRT-D implantation between 2020 and 2024. Data on Inap-S were available for 224 patients, who were classified according to whether they experienced an inappropriate shock. The primary composite outcome was major adverse cardiovascular events (MACE), defined as myocardial infarction, stroke, cardiovascular death, or hospitalization for heart failure (HF). Multivariable logistic regression was used to identify factors associated with Inap-S. Results: Of the 264 patients identified, data on Inap-S were available for 224, of whom nine (4.0%) experienced at least one inappropriate shock. In the overall cohort, the median age was 67 years (interquartile range, 58–74 years), and 176 patients (78.6%) were male. Baseline characteristics were generally similar between the groups. However, patients who experienced Inap-S had a higher rate of non–HF-related hospitalization than those who did not (33.3% vs. 5.6%; P = 0.016). The incidence of the primary composite outcome did not differ significantly between the groups (55.6% vs. 31.5%; P = 0.154). In exploratory multivariable analysis, younger age (odds ratio [OR] per year: 0.940, 95% confidence interval [95% CI]: 0.886–0.997; P = 0.039) and atrial fibrillation (AF) (OR: 5.279, 95% CI: 1.021–27.286; P = 0.047) were associated with Inap-S. Conclusions: In this contemporary cohort, the incidence of Inap-S was low, and no statistically significant association with MACE was observed. Younger age and AF were associated with Inap-S; however, these exploratory findings should be interpreted cautiously because of the small number of inappropriate-shock events and wide CIs. Larger studies are needed to confirm these findings.