During the implantation of transvenous pacemakers and implantable cardiac defibrillators,
the placement of active fixation leads requires the measurement of standard electrical
parameters (sensing, impedance, and capture threshold) to identify the optimal pacing
site before helix deployment into the cardiac muscle. Selecting the optimal site at the
time of implantation is crucial to ensure long-term lead performance and to prevente
potential device malfunctions secondary to threshold elevation or sensing reduction.
Two additional electrical parameters-slew rate and the current of injury-may aid in
selecting the optimal pacing site. However, these parameters have been poorly studied in
the literature and exhibit significant differences. While the slew rate is easily
measurable, as it is automatically determined by the pacing system analyzer (PSA), the
current of injury requires non-standardized, complex, operator-dependent, and
time-consuming manual measurements. Additionally, the slew rate can be assessed before
helix deployment, whereas the current of injury can only be measured after helix
fixation. While the current of injury generally indicates adequate helix fixation, at
least in the acute setting, the significance of slew rate in predicting long-term lead
stability remains uncertain.
The study hypothesis is that the slew rate significantly correlates with sensed
electrical activity at 12 months post-implantation and may therefore serve as a predictor
of optimal long-term lead fixation and performance.
This is a prospective, observational, single-arm, investigator-initiated, multicenter,
non-profit cohort study. Four Italian centers are participating: Ospedale di Fidenza,
Arcispedale Santa Maria Nuova di Reggio Emilia, Ospedale Civile di Piacenza, and Azienda
Ospedaliero-Universitaria di Ferrara.
Patients undergoing pacemaker or ICD implantation with active-fixation atrial or
ventricular leads, either for pacing or defibrillation, will be enrolled. The lead
fixation site (right ventricular apex or septum) and pacing modality (traditional right
ventricular pacing or conduction system pacing) will be determined at the physician's
discretion.
Electrical parameters at implantation-including slew rate, current of injury, sensing,
impedance, and capture threshold-will be measured in all participating centers using the
same pacing system analyzer (PSA) model (Medtronic, Model 2290). Slew rate, sensing,
impedance, and capture threshold will be assessed before and after helix deployment, as
well as after lead fixation.
The current of injury is defined as an increase in ST-segment elevation of at least 5 mV
for ventricular leads and 1 mV for atrial leads compared to baseline in the intracardiac
electrogram (EGM).
All characteristics of the current of injury-including total intracardiac EGM duration,
maximum ST elevation, and maximum ST elevation 80 msec after the first EGM
deflection-will be assessed immediately after helix deployment, as the current of injury
is a dynamic and time-dependent electrical phenomenon.
Following implantation-after device connection and prior to discharge-and throughout the
follow-up period, electrical parameters (sensing, impedance, and capture threshold) will
be assessed using the device programmer provided by the manufacturer of the implanted
device.
Follow-up visits are scheduled at 1 and 12 months post-implantation and may be conducted
either as in-person ambulatory visits or via remote monitoring, according to the standard
clinical practice of each center. During these visits, lead dislodgement and any
significant variations in electrical parameters will also be assessed. The total
follow-up duration is 12 months from implantation.