Novel therapies in cardiac rhythm management: The start of the leadless era

Pacemakers are a successful therapy for bradyarrhythmias, but complication rates are as high as 10-12%, and are mostly associated with the transvenous lead or pacemaker pocket. Leadless pacemakers, miniaturized intra-cardiac pacing devices, have been introduced to eliminate these complications.
This thesis describes the first clinical experience with leadless pacemakers. Initial studies showed that both available leadless pacing systems have similar outcomes with respect to acute complications (4.0-6.5%) – primarily related to the implant procedure (perforations, dislocations, groin complications). An implanter learning curve is observed up until 10 implanted devices. Comparison to conventional therapy with available literature showed somewhat higher acute complications for leadless pacing, but lower mid-term complications in a propensity matched cohort. Definitive comparison to conventional pacing therapy requires randomized controlled trials and long-term follow-up to prove robustness of this novel therapy.
Complications in patients that receive temporary pacing are strikingly high (23-33%). Within this group, transcatheter aortic valve replacement patients can potentially benefit from leadless pacing. The prospective randomized controlled PACE NOW trial is designed to evaluate superiority of leadless pacing over temporary and subsequent conventional pacing therapy with respect to complication rates and need for follow-up procedures.
In the final part of this thesis, the next generation of leadless cardiac rhythm management systems is evaluated. Prototypes of a communicating subcutaneous implantable cardioverter defibrillator (S-ICD) and a leadless pacemaker were co-implanted, showed adequate device-device communication, and delivery of anti-tachycardia pacing (ATP) and shock therapy in pre-clinical animal experiments. Additional and chronic studies are required before transition to clinical studies.