Inappropriate shocks in single-chamber and subcutaneous implantable cardioverter-defibrillators: a systematic review and meta-analysis.
OBJECTIVE
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.


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.
Division of Cardiology, Fondazione Cardiocentro Ticino, Via Tesserete, 48, CH-6900 Lugano, Switzerland.
Angelo
A
Auricchio
Medtronic, PLC, Mounds View, MN, USA.
J Harrison
JH
Hudnall
The Christ Hospital/The Ohio Heart & Vascular Center, Cincinnati, OH, USA.
Edward J
EJ
Schloss
Royal Jubilee Hospital, Victoria, BC, Canada.
Laurence D
LD
Sterns
Division of Cardiology, Kinki University School of Medicine, Osaka, Japan.
Takashi
T
Kurita
Catharina Ziekenhuis, Eindhoven, The Netherlands.
Albert
A
Meijer
Medtronic, PLC, Mounds View, MN, USA.
Dedra H
DH
Fagan
NAMSA, Inc., Minneapolis, MN, USA.
Tyson
T
Rogers
D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004554:Electric Countershock / Q000009:adverse effects* / Q000295:instrumentation* / Q000401:mortality; D004558:Electric Stimulation; D006801:Humans; D016017:Odds Ratio; D011474:Prosthesis Design; D011475:Prosthesis Failure; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
Implantable cardioverter-defibrillator; Inappropriate shocks; Meta-analysis; Subcutaneous ICD; Sudden cardiac death