A novel screening test for inappropriate shocks due to myopotentials from the subcutaneous implantable cardioverter–defibrillator

Abstract

BACKGROUND The subcutaneous implantable cardioverterdefibrillator (S-ICD) is effective in preventing sudden cardiac death. Compared with transvenous ICDs, S-ICDs have a lower rate of inappropriate shocks (IASs) for supraventricular arrhythmias, but such shocks for T-wave oversensing (TWO) and extracardiac myopotentials are more common. No screening tests to identify patients at risk for IAS due to myopotential interference (MPI) currently are available. OBJECTIVE The purpose of this study was to assess the efficacy of a tube exercise test (TET) developed to detect MPI post S-ICD implantation. METHODS TET includes 3 different maneuvers using an exercise tube. S-ICD electrograms were recorded to assess MPI while patients performed each of the maneuvers. RESULTS TET was performed in 43 patients, and MPI was observed in 12 patients (28%). In 10 of the 12 TET-positive patients, the positive vector corresponded with a vector that did not show TWO on standard S-ICD preoperative screening. During median follow-up of 672 days (interquartile range 465-805 days), 3 patients (7%) experienced IAS due to MPI. Importantly, the vector at the time of IAS in all 3 patients passed standard preoperative screening for TWO but was positive with TET. Sensitivity and specificity of TET were 100% and 78%, respectively, and positive and negative predictive values were 25% and 100%, respectively. CONCLUSION Postimplant screening for MPI identified patients at increased risk for IAS. TET may be helpful for guiding optimal programming to prevent IAS.

Inappropriate Subcutaneous Implantable Cardioverter-defibrillator Shocks—A Rare Case of Triple Counting

“… 15 , 17 Other novel screening tools, such as the tube exercise test, can identify patients at risk for inappropriate shocks with positive and negative predictive values of 25% and 100%, respectively. 18 In our study, we present an unusual case where oversensing of P-waves and T-waves resulted in inappropriate ICD shock.…”

Performance of Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) in Chinese Population with Primary Prevention Indications: A Prospective Observational Cohort Study

“…Besides filling the evidence gap of this specific population, the device algorithm and implantation techniques keep being modified while clinical data are published [ 21 – 23 ]. The intermuscular position has been proved to be superior to subcutaneous pockets [ 24 ].…”

Usefulness of lead repositioning to improve subcutaneous electrocardiogram sensing in patients with arrhythmogenic right ventricular cardiomyopathy with subcutaneous implantable cardioverter-defibrillator

“…After S-ICD implantation, the QRS amplitude of S-ECG increased in all sensing vectors and passed preimplant screening. We performed a novel tube exercise test 9 and treadmill exercise test to determine the optimal sensing vector that does not cause MPI. In the results of both exercise tests, no significant MPI and T-wave oversensing were detected when the alternate sensing vector was used ( Figure 3 B).…”