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

BACKGROUND: One 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.

OBJECTIVE: We sought to characterize this ECG finding to detect lead this type of lead malfunction.

METHODS: 138 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.

RESULTS: The 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).

CONCLUSION: The 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.