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.

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.

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.