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Updated: Mar 5, 2026
A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Inappropriate shocks in single-chamber and subcutaneous implantable cardioverter-defibrillators: a systematic review
Angelo Auricchio1, J Harrison Hudnall2, Edward J Schloss3
1Division of Cardiology, Fondazione Cardiocentro Ticino, Via Tesserete, 48, CH-6900 Lugano, Switzerland.
Aims:
Single-chamber (VR-ICD) and subcutaneous (S-ICD) implantable cardioverter-defibrillators are effective to protect patients against sudden death but expose them to higher risk of inappropriate shock (IS). We sought to quantify the annual rate and influencing factors of ISs in VR- and S-ICDs from the literature.
Methods And Results:
PubMed, Embase, and Cochrane Library were searched for full text articles with IS rates. Poisson distribution estimated proportion of patients with ISs; rates were annualized based on follow-up duration. Random effects meta-analysis accounted for study-to-study variation. Out of 3264 articles, 16 qualified for the meta-analysis. Across studies, 6.4% [95% confidence interval (CI) 5.1-7.9%] of patients received an IS per year. Meta-regression analyses demonstrated that IS rates were lower in more recent studies [rate ratio (RR) per year: 0.93, 95% CI: 0.87-0.98; P = 0.01] and trended lower in studies with longer follow-up (RR per year: 0.78, 95% CI: 0.60-1.01; P = 0.06). Use of S-ICDs (RR: 1.81, 95% CI: 0.86-3.81; P = 0.12) and ventricular tachycardia zone programmed on (RR: 1.13, 95% CI: 0.65-1.97; P = 0.66) were not associated with a significantly increased change in risk. The IS rate observed in one of the more recent studies was significantly lower than predicted after accounting for covariates (RR: 0.29, 95% CI: 0.14-0.60; P < 0.001).
Conclusions:
A comprehensive review of the literature shows that 6.4% of patients with ICDs experienced their first IS annually. One of the 16 studies was better than predicted with the lowest reported rate (1.9%) and could not be explained by timing of the study or other covariates.
