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

Abstract

Abstract 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.