Clinical Benefits of the Closed Loop Stimulation in Sinus Node Disease

The benefits of rate-responsiveness on top of dual-chamber pacing still need to be definitively assessed in Sinus Node Dysfunction (SND). Although many rate responsive (RR) sensors have been developed, no large clinical trials evaluated their benefits in terms of clinical endpoints such as clinically relevant atrial fibrillation (AF) and stroke. Electromechanical sensors (piezoelectric accelerometers) have been widely used for their simplicity and overall reliability. However there is some evidence indicating the Closed Loop Stimulation as one of the more efficient and physiological sensors. Two randomized clinical studies have been conducted so far, showing that in the Brady-Tachy Syndrome the CLS algorithm was associated with a significantly lower overall atrial arrhythmia burden as compared both with a DDDR mode based on a standard accelerometric sensor and an atrial overdrive approach. Both studies yielded consistent results, albeit with a parallel and intraindividual comparison designs, respectively. The atrial arrhythmic burden is an important but surrogate endpoint, not necessarily related to long-term clinical outcome. The CLS effects on AF (if any) should be investigated in terms of time to first new onset of clinically relevant AF. In the light of these considerations, it appears interesting to run a large randomized study coherently collecting data on the overall clinical benefit of CLS, primarily in terms of AF and stroke, in a population indicated for pacemaker or ICD and needing dual-chamber pacing due to SND.