Closed loop stimulation in prevention of vasovagal syncope. Inotropy controlled pacing in vasovagal syncope (INVASY): A multicentre randomized, single blind, controlled study

Eraldo Occhetta, Miriam Bortnik, Roberto Audoglio, Corrado Vassanelli, Pierluigi Roncarolo, Leandro Chiodi, Marco Marcolongo, Davide Torta, Marco Zanetta, Guiseppe Boriani, Raimondo Pirisi, Antonio Mazza, Paolo Marconi, Diran Igidbashian, Salvatore Romano, Ruggero Manfredini, Claudio Tondo, Massimo Arlotti, Marcello Chimienti, Luigi ZamparelliLuciano Cioffi, Angelo Carboni, Maria Grazia Bongiorni, Rocco Polimeni, Sergio Sermasi, Giovanni Del Giudice, Adriano Croce, Giovanni Batista Tola, Pierfranco Terrosu, Paolo Bellotti, Massimo Gazzarata, Luigi Libero, Marcella Jorfida, Mauro Bensoni, Daniela Barbieri, Sergio Lombroso, Antonio Galati, Jorge Salerno, Salvatore Caico, Enzo Maria Bianchi, Renato Glenzer, Francesco Zolezzi, Roberto Negro, Massimo Sassara, Fernando De Luca

Research output: Contribution to journalArticlepeer-review


Objectives: To determine whether dual-chamber rate-adaptive Closed Loop Stimulation (CLS) could prevent recurrence of Vasovagal Syncope (VVS). Background: During VVS, an increase in myocardial contractility associated with a reduction of ventricular filling produces an increase in baroreceptor afferent flow and a consequent decrease in the heart rate. The CLS algorithm is a form of rate-adaptive pacing, which responds to myocardial contraction dynamics, by measuring variations in right ventricular intracardiac impedance: during an incipient VVS it could increase paced heart rate and avoid bradycardia, arterial hypotension and syncope. Methods: Fifty patients (27 males, mean age 59 ± 18 year) with severe and recurrent vasovagal syncope and positive Head Up Tilt Test (HUTT) with cardioinhibition, received a CLS pacemaker (INOS2, Biotronik GmbH Co., Germany). The primary end point was recurrence of two VVSs during a minimum of 1 year of follow-up. Randomization between DDD-CLS and DDI mode (40 bpm) pacing was performed only during the first stage of the study (first year): 9/26 randomized to DDI mode (control group) and 17/26 in DDD-CLS mode. All the 24 patients recruited in the second stage of the study (second year) were programmed in DDD-CLS mode. Results: Of the nine patients randomized to the DDI mode, seven had recurrences of syncope during the first year. At the end of the first year the nine patients were reprogrammed to the CLS mode and no syncope occurred after reprogramming. The 41 patients programmed to CLS had a mean follow-up of 19 ± 4 months: none reported VVS, only four (10%) reported occasional presyncope and their quality of life greatly improved. Positive HUTT at the end of the first year failed to predict the clinical response to CLS pacing. Conclusions: The study demonstrates the effectiveness of CLS pacing in preventing cardioinhibitory VVS. A possible placebo effect of pacemaker implantation occurred in 22% of patients.

Original languageEnglish
Pages (from-to)538-547
Number of pages10
Issue number6
Publication statusPublished - Nov 2004


  • Closed loop stimulation
  • DDD pacing
  • Vasovagal syncope

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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