Decrease in Amplitude of Intracardiac Ventricular Electrogram and Inappropriate Therapy in Patients With an Implantable Cardioverter Defibrillator

Abstract

SUMMARYIntracardiac electrograms are important for discrimination of tachyarrhythmia by implantable cardioverter defibrillators (ICD). A low R-wave can cause not only undersensing of ventricular tachyarrhythmia but also inappropriate discharges due to oversensing of unexpected signals because of its characteristic sensing algorithm. Therefore, this study aimed to investigate adverse events associated with R-wave amplitude. We included 115 consecutive patients followed-up over one year after implantation of a transvenous ICD system. The status of the ICD was checked every 3 months and intracardiac ventricular electrograms were analyzed. The decrease in R-wave amplitude was high in arrhythmogenic hypertrophy cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy (ARVC), and sarcoidosis. Low R-waves (< 5.0 mV) were observed in 13 patients at a follow-up of 15 ± 16 months after implantation, and the mean R-wave was 3.0 ± 0.8 mV. The frequency of low R-waves was high in ARVC (38%), sarcoidosis (33%), and dilated cardiomyopathy (17%). All of the dilated cardiomyopathy patients with low R-waves had severe left ventricular dysfunction. Inappropriate ICD therapy resulting from T-wave oversensing occurred in 7 patients and the R-wave was < 5.0 mV in 6 of the patients. The frequency of inappropriate therapy was high in patients with sarcoidosis. In 3 patients, inappropriate therapy caused ventricular tachyarrhythmia. In conclusion, decreases in Rwave amplitude occurred in some progressive cardiac disorders and caused inappropriate ICD discharges having arrhythmogenicity. Physicians should attempt to obtain a high Rwave amplitude during ICD implantation and careful follow-up is required, especially in patients with ARVC or sarcoidosis. (Int Heart J 2006; 47: 363-370)

Failure of ICD therapy in lethal arrhythmogenic right ventricular cardiomyopathy type 5 caused by the TMEM43 p.Ser358Leu mutation

“…From ICD interrogations, under-sensed low-amplitude VF seems to be the reason why long-term ARVC patients experience SCD without any ICD therapy 9, 10. This phenomenon may also play a role in our 3 index patients, although there was only 1 case in which we had available ICD recordings that documented intermittent under-sensed low-amplitude VF.…”

Implantable Defibrillators in Long QT Syndrome, Brugada Syndrome, Hypertrophic Cardiomyopathy, and Arrhythmogenic Right Ventricular Cardiomyopathy

“…90 In extensive RV disease, difficulty with lead placement or perforation may occur. A coronary sinus lead for pacing/sensing has been used in the event of low R waves.…”

Impact of Pacing and High-Pass Filter Settings on Ventricular Bipolar Electrograms in Implantable Cardioverter Defibrillator Systems - Implication of Predictors for Inappropriate Therapy Caused by Oversensing of Repolarization Electrograms -

“…They demonstrated that the frequency of low R waves and also inappropriate therapy was high in arrhythmogenic right ventricular cardiomyopathy (ARVC) (38%), sarcoidosis (33%), and DCM (17%). 13 Wichter et al also suggested that particular attention should be paid to the progressive loss of the R wave amplitude during follow up in patients with ARVC. 14 Bramanti et al also reported that ARVC patients with pacemakers or ICDs should be closely followed in order to avoid any possible undersensing due to the extremely prolonged ventricular depolarization.…”