Difficulty enrollment; higher than planned patient attrition and data attrition

The APPROPRIATE study will compare differences in functional capacity (peak VO2) between chronotropically incompetent patients randomized to receive rate responsive pacing driven by either the minute ventilation (respiration-based) sensor or an accelerometer (motion-based).

Inclusion Criteria:

• Meets or met current pacemaker implantation indications
• Willing and capable of providing informed consent for participation
• Receiving a dual-chamber pacemaker or previously received a dual-chamber pacemaker with active atrial and ventricular leads
• Plans to remain in the long-term care of his/her enrolling physician and is available for study follow-up for three months post-enrollment

Exclusion Criteria:

• Mobitz II second degree heart block

• Third degree heart block

• Chronic atrial fibrillation or uncontrolled atrial arrhythmias within the past 90 days prior to consent

• Neuromuscular, orthopedic, or vascular disability that prevents normal walking or weight carrying (e.g., intermittent claudication, arthritis, residual stroke weakness, need for a wheelchair or walker)

• A symptom-limited exercise protocol is thought to be dangerous or contra-indicated, including but not limited to changing pattern of chest discomfort or uncontrolled arrhythmias

• Pulmonary disease as defined by any one of the following:

  • Forced Vital Capacity (FVC) or Forced Expiratory Volume in one second (FEV1) < 60% of predicted values
  • Use of two or more pulmonary inhalers
  • Use of supplemental oxygen
  • Chronic use of oral steroids for pulmonary disease treatment

• Life expectancy is less than 12 months due to other medical conditions, per physician discretion

• Has or indicated for an implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D)

• Currently enrolled in another investigational study that would directly impact the treatment or outcome of the current study.

• Younger than 18 years of age

• Pregnant or planning to become pregnant during the study (method of assessment upon physician's discretion)

• Unable or unwilling to comply with the protocol requirements

Early termination leading to small numbers of subjects analyzed. As the study was stopped early, the primary objective is underpowered.