Long-term risk of replacement of cardiovascular implantable electronic devices following external cardioversion

Introduction

External cardioversion (ECV) with transthoracic shock is a recommended and important part of the rhythm control strategy regardless of cardiovascular implantable electronic devices (CIED). Studies and case reports have demonstrated rare, but serious CIED malfunctions related to the ECV procedure. However, follow-up data on contemporary CIEDs undergoing ECV procedures are limited. The aim of this study is to investigate the long-term risk of generator replacements following an ECV procedure.

Methods

All CIED implants and surgical re-interventions in Denmark were identified in the Danish Pacemaker and ICD Register from January 2005 to April 2021. The ECV procedures were identified in the Danish National Patient Registry from January 2010 to February 2019. For each patient undergoing ECV, five matched (age, sex, and type of CIED) controls without previous ECV were identified. Time to generator replacement was estimated using competing risk analyses, with death, extraction and up-/down-grade being competing events. Risks were estimated by the pseudo-observation method.

Results

We identified in total 3,924 ECV-events in 2,610 CIED patients with 74.4% male. Mean age of patients at first ECV-procedure were 68.6±11.7 years, and median implant time was 1.5 year. The type of CIED included 50% of pacemakers, 28% of Implantable Cardioverter Defibrillators, and 22% of Cardiac Resynchronization Therapy-systems. During the first 5 years of follow-up, 451 (17.3%) of the shock-exposed devices were replaced vs. 2,000 (15.2%) of the unexposed devices. The relative risks (RR) of device replacement were 1.43 (95% CI: 0.5; 2.4) after 12 months, 1.44 (95% CI: 0.1; 2.8) after 24 months, and −0.53 (95% CI: −2.8; 1.7) after 5 years. The cumulated incidence of first endpoint: Replacement, death, extraction, and up-/down-grade are illustrated in Figure 1. A larger proportion of patients died in the shock-exposed group with n=427 (16.4%) compared to n=1,588 (12.2%) in the unexposed group during 5-years of follow-up with RR=3.2 (95% CI: 1.2; 5.3) of dead before other events.

Conclusion

Contemporary CIEDs do not indicate different risk of generator replacement following external cardioversion with transthoracic shocks. Shock-exposed device patients were more prone for extraction and death.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): This is work was financed by Department of Cardiology, Aalborg University Hospital and supported by Karl G. Andersen foundation.

External cardioversion of atrial fibrillation and flutter in patients with cardiac implantable electrical devices

Funding Acknowledgements

Type of funding sources: None.

Introduction

Atrial tachyarrhythmias are often treated with external cardioversion (ECV) with direct current shocks in patients with potentially electrically sensitive cardiovascular implantable electronic devices (CIED). Long-term follow-up data on contemporary pacemakers and implantable cardioverter defibrillators (ICD) undergoing ECV is sparsely described. This study investigated shock-related complications and impact on CIEDs.

Methods

All ECV procedures of atrial fibrillation and flutter from 2010 to 2020 in patients with CIED performed at a tertiary hospital (Denmark) were identified in the Danish National Patient Registry. Data on device interrogation before and after ECV and procedure-related complications were retrieved retrospectively by review of medical records.

Results

We analysed 664 ECV-events performed in 362 CIEDs, median implant time 1.5 year. Mean age of patients at first ECV-event were 69.4±9.7 years and 72.2% were men. We identified two cases of major programming changes and two cases of premature battery depletion (≤3 years after generator implant) following ECV. Minor shock-related device changes were found for impedances, atrial sensing values and pacing thresholds of right ventricle lead. In two cases increased pacing threshold of right ventricle leads following ECV triggered exit-blocks after few months. No patients died due to shock-related device dysfunctions.

Conclusion

Following external cardioversion with transthoracic direct current shocks, sporadic (<1%) but potentially critical changes in device function were identified in patients with contemporary pacemakers and implantable cardioverter-defibrillators. The present study suggests that routine post-cardioversion device interrogation is imperative for patient safety.