Association Between Current of Injury Magnitude and Intraoperative R-Wave Amplitude Fluctuation After Pacing Lead...

Pacing threshold adequacy and lead stability can be predicted from the magnitude of the current of injury (COI) immediately after active fixation. However, intraoperative R-wave amplitude often fluctuates despite sufficient COI.

The authors aimed to assess whether R-wave amplitude fluctuations are associated with the COI magnitude and can be predicted from early electrogram (EGM) patterns.

EGMs of 109 cases of right ventricular pacing on the septum were continuously recorded from implantation to generator connection. R-wave amplitude fluctuation patterns were categorized as Dipper type (transient decrease followed by an increase), Riser type (continuous increase), and Other type. The primary outcome was a favorable R-wave amplitude increase, defined as the final value exceeding the initial value.

Among the 109 cases, 65 (60%) exhibited Dipper-type and 41 (38%) showed Riser-type R-wave fluctuation patterns. In the Dipper-type patterns, initial EGMs showed R-wave amplitude < COI, which subsequently shifted to R-wave amplitude > COI patterns. Favorable amplitude increases occurred in 34 (52%) of the Dipper-type cases and were associated with shorter times to the lowest R-wave amplitude, with 6 minutes being identified as optimal for prediction (sensitivity: 0.82, specificity: 0.61). All the Riser-type patterns exhibited favorable amplitude increases, with consistent R-wave amplitude > COI patterns.

Most intraoperative R-wave amplitude fluctuations in successful lead implantations follow Dipper- or Riser-type patterns. Favorable R-wave amplitude increases can be predicted within 6 minutes post fixation using early EGM patterns.