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

BackgroundOne of the most common modes of lead failure is outer 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 has been observed with insulation breaches. We sought to characterize this ECG finding to detect lead this type of lead malfunction. Methods138 transvenous leads were analyzed (88 with known malfunction and 50 normal leads). The highest amplitude (any of 12-leads on standard ECG, 10mm/mV, GE Marquette) of a bipolar pacing stimulus on ECG was recorded and compared to a control dataset of newly implanted leads. An ROC curve for maximum ECG bipolar pacing stimulus amplitude was generated for prediction of lead functional status (normal vs malfunction). ResultsThe cohort (49% females, 34% non-white) had an average age of 67 {+/-} 16 years at implant. 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 (15.06 {+/-} 13.533mm or 7.89 {+/-} 7.56mm per V, p<0.001) compared to those of normal leads (2.54 {+/-} 1.265mm or 0.86 {+/-} 0.41mm per V). An EKG stimulus amplitude cut-off at 3.5mm for the prediction of this type of lead malfunction demonstrated a sensitivity of 86.4% and a specificity of 76%. 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). ConclusionFor a given output, the maximum amplitude of a bipolar pacing stimulus on ECG is significantly lower in normal functioning leads compared to those with known malfunction due to insulation breach. This simply-derived variable demonstrated good accuracy at identifying this lead failure due to insulation breach and exposed electrodes.