Clinical observations with Closed Loop Stimulation pacemakers in a large patient cohort: the CYLOS routine...

Closed Loop Stimulation (CLS) pacemakers couple pacing rate to myocardial contraction dynamics by monitoring unipolar right ventricular impedance on a beat-to-beat basis. The aim of this large-scale registry was to evaluate the safety and efficacy of the CLS therapy under clinical routine conditions.

A total of 706 patients was enrolled in the clinical investigation 'Registry: CYLOS Routine Documentation' (RECORD) at 57 investigational sites in Europe and Hong Kong. Not to interfere with clinical routine and therapeutic decisions of health care providers, the registry was implemented as a part of the standard follow-up schedule. Two follow-ups were conducted within 12 months of enrolment in order to evaluate typical programming of CLS-related parameters, reasons for their later reprogramming, frequency of patient intolerance to CLS, and physicians' satisfaction with medical benefits and technical performance of CLS in each patient. The investigators' medical and technical notes on CLS rated it excellent in ~80% of patients, poor in 1.4% (medical benefit) or 0.5% (technical performance), and adequate in rest of the patients. Closed Loop Stimulation functionality was not influenced by pacing site variation within the right ventricle (septal, outflow tract) or by advanced heart failure (New York Heart Association classes II-IV). Permanent or temporary CLS deactivation was undertaken for various reasons in 6.2% of patients. Signs of intolerance to CLS or rate-adaptive pacing were reported by 2.3% of patients. Reprogramming of CLS-related parameters was seldom undertaken, with >90% of pacemakers operating with default settings in the long term.

Clinical performance of CLS was very satisfactory in the large cohort studied.