Efficacy of a Pacemaker Algorithm in Promotion of the Intrinsic Heart Activity.

IntAct, Study on Promotion of Intrinsic Activity.

The purpose of this study is to provide evidence that the Refined Ventricular Pacing Algorithm leads to clinically relevant reduction (at least 50% reduction) of the incidence of ventricular pacing.

Electrical stimulation in the apex of the right ventricle ( ventricular pacing) usually improves the heart function of patients with a pacemaker and can even be life-saving. However, evidence is accumulating that ventricular pacing may also have undesired long-term cardiac effects. Therefore, it makes sense to limit ventricular pacing to the absolute required minimum. The functionality RVP (Refined Ventricular Pacing) in the C-series 2nd generation pacemakers of Vitatron B.V. Arnhem, the Netherlands is designed to reduce ventricular pacing.

After implantation of the Vitatron C50 D model C50A2 (pacemaker) or Vitatron C60 DR model C60A2 (pacemaker) and a 4-6 weeks stabilization period, proper functioning of pacemaker and leads (stimulation- and sensing parameters) is checked. The pacemakers will be programmed according to predefined settings.

In the following 4-weeks Baseline period diagnostic data (atrial fibrillation burden and percentage of ventricular pacing (% VP)) are collected in the pacemaker memory. Based on these data, patients will be excluded from further participation (patients with more than 15% atrial fibrillation) or subdivided into three groups: (a) < 30% VP (30- VP group), (b) >30% VP, Sick Sinus Syndrome and normal conductivity (SSS group), (c) >30% VP, 1st or 2nd degree AV block. Patients in these three groups will be treated for 4 weeks alternatively with the RVP functionality switched ON or OFF. The order will be determined by randomization. At the end of these two cross-over periods the % VP and the judgment of the patients of the last period will be assessed. Adverse events will be recorded from the moment of study enrolment.

Inclusion Criteria:

• Patients shall be willing to sign the Patient Informed Consent for this study
• Patients shall have at least one of the following indications for a pacemaker: - Sick Sinus Syndrome with normal QRS complexes
• First degree AV block with a PR interval <_220 ms for patients <_ 70 years of age, or <_ 260 for patients over 70 years
• Second-degree AV block, mobitz I (wenckebach) or mobitz II
• Patients shall be available for follow-up for the duration of their participation.

Exclusion Criteria:

• Patients involved in another investigation study conducted in parallel to this study
• Patients younger than 18 years of age and/or patients that do NOT meet other local requirements for participation
• Pregnant patients
• Patients with lead integrity problems (and the lead is not being replaced)
• Patients with persistant AF
• Patients with a complete AV block
• Patients with NYHA (New York Heart Association0 class III and IV
• Patients who underwent thoracic surgery in the last three months or are expected to have in the near future
• Patients with a 2:1 block
• Patients with a life expectancy less than half a year