Conduction Disorder of the Heart, Heart Block, Syncope
Conditions
Keywords
syncope, fainting, implantable loop recorder, pacemaker, heart block, bifascicular heart block
Brief summary
Syncope affects about 50% of Canadians, is the cause of 1 - 2% of all emergency room visits, and probably is responsible for CDN $250 million in health care spending each year. It is associated with decreased quality of life, trauma, loss of employment, and limitations in daily activities. It is a particular problem for older people, partly because of increased frailty, and partly because of a difficult differential diagnosis. One of the causes in older adults is intermittent complete heart block in the setting of bifascicular heart block, but they may also faint due to a variety of tachyarrhythmias, sick sinus syndrome, and several neurally mediated syncopes. Often treatment decisions should be made before the true cause is apparent.
Detailed description
There are two general approaches to the patient with syncope and bifascicular block, a common substrate for intermittent heart block. The first is to assume that intermittent heart block is the cause, and simply implant a pacemaker. The second is to implant a digital ECG loop recorder with a lifespan of 2 - 3 years, determine the rhythm abnormalities during the next faint, and treat accordingly. Both approaches expose patients to a risk of fainting and its sequelae, and both carry device-related complications.Which approach is superior is unknown.
Interventions
PROCEDUREpacemaker
A single or dual chamber pacemaker will be implanted according to the manufacturer's instructions for use with standard techniques. Either a single or dual chamber pacemaker will be permitted according to local practice unless the patient is in chronic or persistent atrial fibrillation, in which case a single chamber pacemaker will be used. The pacemaker configuration will be at the discretion of the investigator. Single chamber ventricular pacemakers will be programmed to activity responsiveness off in VVI mode, rates 50-120 bpm. Dual chamber pacemaker programming will be to DDD mode (50-120) with mode switch on.
PROCEDUREimplantable loop recorder
The implantable loop recorder will be programmed for automatic detection using settings of Low Heart Rate \<50 bpm, High Heart Rate \>165 bpm, and Pause \> 3 seconds.
Sponsors
Vanderbilt University
Canadian Institutes of Health Research (CIHR)
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
Inclusion criteria
-Patients are eligible if they have: * \>1 syncopal spell within 1 year preceding enrollment, and * bifascicular block on a 12-lead ECG, and * Age \> 50 years and * written informed consent. Syncope will be defined based on history using a standardized form.
Exclusion criteria
-Patients will be excluded if they have criteria related to study strategies, including: 1. previous pacemaker, ICD, or Implantable Loop Recorder in situ, 2. ACC/AHA/HRS Class I indication for permanent pacing or ICD implantation, 3. left ventricular ejection fraction \< 35% mandating ICD therapy, 4. contra-indication to a transvenous pacemaker such as artificial tricuspid valve or active sepsis. -Patients will also be excluded if a potential competing cause of syncope poses a threat to life, such as: 5. hypertrophic cardiomyopathy, 6. documented sustained ventricular tachycardia or 7. inducible, sustained monomorphic ventricular tachycardia on EP study. -They will be excluded if they have: 8. a history of myocardial infarction within 3 months prior to enrollment, and 9. a major chronic co-morbid medical condition that would preclude 24 months of follow-up.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| The primary outcome measure will be a composite of Major Adverse Study-Related Events (MASRE) in a 2-year observation period. | 2 years | MASRE will capture the major consequences ensuing from both strategies, including 1) syncope, 2) symptomatic bradycardias, 3) asymptomatic complete heart block, 4) acute and chronic pacemaker and ILR complications, and 5) death. |
Secondary
| Measure | Time frame |
|---|---|
| Secondary outcome measures will include total number of syncopal spells. | 2 years |
| Secondary outcome measures will include the likelihood of a first recurrence of syncope. | 2 years |
| Secondary outcome measures will include the physical trauma due to syncope. | 2 years |
| Secondary outcome measures will include quality of life of the participants. | 2 years |
Countries
Canada, Japan, Malaysia, United Kingdom, United States
Outcome results
None listed