The Automated Subcutaneous Implantable Cardioverter-Defibrillator Screening in Patients With Leadless Pacemakers

The number of leadless pacemakers (LPMs) implantations has seen a major growth in recent years. Indications for LPMs often overlap with indications for subcutaneous implantable cardioverter-defibrillators (sICDs), as they are mostly recommended in patients in whom transvenous devices are deemed ineligible or contraindicated. Before sICD implantation, the patient should pass screening to verify the stability of QRS morphology in intrinsic and paced rhythms. The aim of this study was to evaluate the percentage of positive sICD screening in patients with a previously implanted LPM and evaluate the concordance between the vectors during the intrinsic and paced rhythm.

Twenty-two patients who underwent implantation of the ventricular LPM from May to October 2024 were included in the present study. After the implantation, automated sICD screening was performed using the dedicated system, across 2-4 body positions, both during intrinsic and paced rhythms, in nominal, and emergency output.

All patients had the devices implanted in the interventricular septal location. Screening for QRS indicated that 94.1% of patients fulfilled the criterion for implantation of sICD in at least one vector during intrinsic rhythm, while only 23.8% and 28.5% passed screening during nominal and emergency pacing outputs, respectively. Positive screening concordance in at least one vector was observed in 23.5% of patients.

Despite almost all patients having undergone successful screening during intrinsic rhythm, the low rates of positive QRS assessment were observed during pacing, what might raise potential concerns for an optimal coexistence of LPM and sICD in daily clinical practice.