The DDDR closed loop stimulation for the prevention of vasovagal syncope: results from the INVASY prospective feasibility registry.

Abstract

The contraction dynamics of the ventricular myocardium are affected before and during vasovagal fainting suggesting that the Closed Loop Stimulation (CLS) pacemaker could be useful for the treatment of these patients. CLS is a new concept of heart rate modulation in cardiac pacing. The pacemaker INOS(2) CLS (Biotronik, Germany) derives its information for heart rate optimization from myocardial contraction dynamics, by measuring right ventricular intracardiac impedance. The pacemaker becomes an integral part of the circulatory regulation and, therefore, reacts appropriately to different cardiovascular demands. In a prospective registry, 34 patients with a history of recurrent vasovagal syncopal events were implanted with INOS(2) DDDR CLS pacemakers. The aim of the study was to evaluate both long term clinical outcome, including the first recurrence of syncope, with DDDR-CLS pacing and acute precipitation of vasovagal fainting with DDDR-CLS mode compared with DDD during head up tilt testing. During a follow up period of 12-50 months, 30 patients experienced no further syncopal events in daily life; 1 patient had no syncope but night palpitations, which were eliminated by pacemaker reprogramming; 2 patients had presyncopal episodes but not syncopes; 3 syncopal recurrences occurred in one patient in chronic atrial fibrillation, possibly not an ideal candidate for implantation. Further studies for detailed understanding of the preventive mechanism of DDDR-CLS pacing in vasovagal syncope are warranted. A randomized multicentre prospective new study (INotropy controlled pacing in VAsovagal SYncope: INVASY) is now in progress to confirm the beneficial effect of DDDR-CLS pacing in a larger group of patients with recurrent vasovagal syncope.