Prevention of inappropriate therapy in implantable defibrillators: A meta-analysis of clinical trials comparing single-chamber and dual-chamber arrhythmia discrimination algorithms

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Abstract

Introduction

A proposed benefit of dual-chamber arrhythmia discrimination is a reduction in inappropriate therapy in implantable cardioverter-defibrillators (ICDs). The aim of this meta-analysis was to establish whether dual-chamber arrhythmia discrimination algorithms reduce inappropriate device therapy.

Methods and results

Public domain databases, MEDLINE, EMBASE, and Cochrane Register of Controlled Trials, were searched from 1996 to 2006. Two investigators abstracted data independently. Pooled estimates were calculated using both fixed-effects and random-effects models. We retrieved 5 prospective studies comparing dual-chamber with single-chamber arrhythmia discrimination, accumulating data on 748 patients. Pooled per-patient based analysis demonstrated that the number of patients receiving inappropriate ICD therapy was not different between single- and dual-chamber devices (odds ratio [OR] 1.23; 95% CI, 0.83 to 1.81; p = 0.31). Per-episode based analysis demonstrated a favoring benefit for dual-chamber arrhythmia discrimination (OR 0.64; 95% CI, 0.52 to 0.78; p < 0.001). A mean reduction of 1.1 inappropriately treated atrial episodes per patient was observed with dual-chamber arrhythmia discrimination (p < 0.001).

Conclusions

Dual-chamber arrhythmia discrimination is associated with a reduction in the number of inappropriate treated episodes. The number of patients who experience inappropriate therapy is not reduced by dual-chamber discrimination.

Introduction

The implantable cardioverter-defibrillator (ICD) has evolved to standard therapy for the prevention of sudden cardiac death in patients with reduced left ventricular function [1], [2], [3], [4], [5]. Despite the accuracy and effectiveness in the diagnosis and treatment of ventricular tachyarrhythmias, the ICD may also result in excess morbidity [6], [7], [8], [9]. One of the factors is inappropriate therapy for atrial tachyarrhythmias or other events. To avoid inappropriate therapy, several detection enhancements were developed to discriminate between atrial and ventricular tachyarrhythmias. In single-chamber devices, discrimination is based on sudden onset, RR interval stability, and electrogram morphology. Theoretically, dual-chamber ICDs have the opportunity to improve arrhythmia discrimination over single-chamber devices by the addition of atrial information. Some studies which compare single-chamber and dual-chamber devices reported small or even non-existent advantages of dual-chamber arrhythmia discrimination [10], [11], [12]. Recent studies support an actual benefit of dual-chamber devices over single-chamber devices [13], [14], [15]. However, conclusive evidence of improved arrhythmia discrimination by dual-chamber ICDs is still lacking. We performed a systematic review and meta-analysis of controlled studies that compared the performance of dual-chamber and single-chamber arrhythmia discrimination, with the purpose of establishing whether dual-chamber arrhythmia discrimination algorithms reduce inappropriate device therapy.

Section snippets

Search strategy

Controlled clinical trials comparing single-chamber with dual-chamber arrhythmia discrimination algorithms implemented in ICDs were identified. Public domain databases including MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for all published articles from January 1996 to June 2006 related to arrhythmia discrimination by the ICD. The search was restricted to humans and English language literature. The data limits were chosen because the dual-chamber ICD

Search results

A total of 554 references from all databases were found. A total of 458 potentially relevant reports of clinical trials with implantable defibrillators were screened, and 394 were excluded based on titles and abstracts. For detailed evaluation, full-text versions of the remaining 64 reports were retrieved. Of these, 5 reports of 5 controlled studies were included for this analysis.

Qualitative findings

Our search identified 6 controlled clinical studies comparing dual-chamber with single-chamber arrhythmia

Discussion

This meta-analysis demonstrated a significant reduction in the number of inappropriately treated atrial episodes with dual-chamber arrhythmia discrimination. Pooling controlled studies together, dual-chamber arrhythmia discrimination was associated with a 36% reduction in inappropriately treated episodes as compared with single-chamber arrhythmia discrimination. However, the number of patients who received inappropriate therapy was not affected by dual- or single-chamber arrhythmia

Conclusion

This meta-analysis shows that dual-chamber arrhythmia discrimination significantly reduces the number of inappropriately treated atrial episodes compared to single-chamber devices. However, the amount of patients receiving inappropriate therapy was similar between groups.

Acknowledgement

The authors thank Dr P.A. Friedman and Dr M. Glikson for sharing unpublished results of the Detect SVT Study. We thank Dr D. Bänsch and mr. R. Ocklenburg for giving additional data of the 1 + 1 Trial.

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    DAMJ Theuns received research grants from Biotronik (Netherlands) and Guidant (Netherlands). DAMJ Theuns is a consultant for Cameron Health (USA). L Jordaens received research grants and speaker fees from Biotronik, Guidant, Medtronic, Sorin, and St Jude Medical.

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