Real-World Experience with Combined Leadless Pacemaker and Subcutaneous Implantable Cardioverter-Defibrillator Therapy: A Multicenter Study in Japan

Background Combined leadless pacemaker (LLPM) and subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy is generally contraindicated because of potential device–device interaction but may be required in selected patients. Objective We evaluated the real-world safety and outcomes of this combined strategy in Japan. Methods We conducted a retrospective multicenter survey and identified patients who underwent combined LLPM–S-ICD therapy between 2016 and 2025. Procedural details, device performance, adverse events, and long-term outcomes were analyzed. Results Twenty patients (70 ± 14 years, 80% male) from 15 institutions were included. ICD indications were secondary prevention in 17 patients. Bradyarrhythmias included sinus node dysfunction (n=9) and atrioventricular block (n=11), and all implanted LLPMs were VVI devices. Ten patients had comorbidities, including chronic infection, malignancy, severe dermatologic disorders, or neurodegenerative disease. The main indications for combined therapy were prior device infection, high infection risk, limited venous access, and severe tricuspid regurgitation. LLPM implantation preceded S-ICD in 13 patients, and S-ICD implantation preceded LLPM in 7. The lead was positioned on the left parasternal in 17 patients and right in 3. Defibrillation testing was performed in 14 patients and was successful at 40–80 J, without VF undersensing or LLPM malfunction. During a median follow-up of 492 days, appropriate S-ICD shocks occurred in four patients and inappropriate shocks in five. No clinically significant device–device interaction, device infection, or arrhythmic death was observed. Conclusion Combined LLPM–S-ICD therapy was feasible, with no device–device interaction observed in this small cohort; larger studies are needed to assess safety.