Accurate Detection of Lead Malfunction from ECG-derived Bipolar Pacing Stimulus Amplitude

BackgroundOne common mode of lead failure is insulation breach which may result in myopotential noise and device malfunction. “Pseudo-unipolarization” of bipolar pacing stimuli, as observed from a routine 12-lead ECG due to stimulus current leak has been observed with insulation breaches.ObjectiveWe sought to characterize this ECG finding to detect lead this type of lead malfunction.Methods138 transvenous leads were analyzed, including 88 with known malfunction and 50 normal leads. The amplitude of a bipolar pacing stimulus on ECG was recorded and compared to a control dataset of newly implanted leads with bipolar stimuli normalized for output.ResultsThe malfunction group consisted of 61% RA and 39% RV leads with mean pacing output 2.74V at 0.5ms. There was a significant difference in ECG bipolar stimulus amplitudes at time of identification of failure (7.89 ± 7.56mm per V, p<0.001) compared to those of normal leads (0.86 ± 0.41mm per V). ROC curve for the prediction of lead malfunction based on absolute EKG amplitude displayed an area under curve of 0.93 (95% CI 0.891- 0.969). When normalized for programmed stimulus output, a cutoff of 5mm/V demonstrated a sensitivity of 91% and a specificity of 92% (AUC 0.967 95% CI 0.938-0.996).ConclusionThe maximum amplitude of a bipolar pacing stimulus on ECG is significantly lower in normal functioning leads compared to those with known malfunction. This simply-derived variable demonstrated good accuracy at identifying lead failure due to insulation breach.