Spectrum of issues detected by an ICD diagnostic alert that utilizes far-field electrograms: Clinical implications

Implantable cardioverter-defibrillator (ICD) lead failure is one of the major causes of inappropriate shocks. Algorithms have been developed by manufacturers to identify ICD lead failure and avoid inappropriate shocks. The SecureSense RV Lead Noise Discrimination (St Jude Medical, St Paul, MN) algorithm is designed to differentiate oversensing due to lead failure from ventricular arrhythmias and withhold inappropriate therapies. Several non-lead failure-related issues can trigger the SecureSense automated algorithm.

Our objective was to explain the SecureSense algorithm in a detailed fashion, highlighting examples of SecureSense alerts triggered by non-lead failure-related issues.

This is a nonrandomized observational case series. SecureSense-triggered alerts from 3 ICD device clinics were analyzed, and representative examples of SecureSense triggers due to non-lead failure-related issues were chosen to explain the function and malfunction of this algorithm.

The series includes 8 cases of SecureSense alerts triggered by non-lead failure-related issues---myopotential oversensing (1), P-wave oversensing (1), T-wave oversensing (1), loss of capture (1), R-wave undersensing (1), timing cycle issues (2), and cross talk (1)---and 1 case of failure of the algorithm to appropriately identify lead failure and prevent ICD shocks.

Lead failure detection algorithms such as the one assessed in this study have an inherent risk of false-positive and false-negative detections. The latter might have fatal consequences. The true accuracy of these algorithms needs to be evaluated in large-scale real-life prospective clinical studies.