Better predictors of successful His-bundle ablation analysis of first shocks

We have reported here that a longer HV interval in association with a larger His amplitude yields a high rate of success when used to position the ablating catheter for His-bundle ablation. Additionally, we have shown that double discharge shocks are more effective than single discharge shocks, and that negative polarity is more effective than positive polarity. The use of bipolar or tripolar, and not quadripolar catheters, was also associated with a higher success rate. In our institution, using a bipolar catheter, we attempt to record an HV interval greater than 55 msec and a His amplitude greater than 0.35 mV. When both of these criteria are fulfilled, we use 3 to 4 joules per kg, and a single discharge shock. When one or the other of these criteria are not fulfilled, we use the double discharge shock method. Using these techniques, we have achieved successful His-bundle ablation with only one shock in all but one of the most recent 21 consecutive patients.