Syncope: Pacing or Recording in the Later Years

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.