From the Guidelines
Electrophysiological (EP) studies play a limited role in the evaluation of symptomatic bradycardia and are generally not recommended as first-line diagnostic tools. EP studies are typically reserved for specific situations where the cause of bradycardia remains unclear after non-invasive testing or when there is suspicion of conduction system disease that requires further characterization, as stated in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Key Points to Consider
- In patients with symptomatic bradycardia, the initial evaluation should include a thorough history, physical examination, 12-lead ECG, and ambulatory monitoring (such as Holter monitors or event recorders) 1.
- EP studies may be considered when these initial evaluations fail to establish a clear correlation between symptoms and bradycardia, or to assess the extent of conduction system disease in patients with suspected infranodal block 1.
- The use of an EP study has almost exclusively been examined in patients with syncope or presyncope, and is generally an adjunctive tool in the evaluation of patients in whom bradycardia is suspected but has not been documented after noninvasive evaluation 1.
- During an EP study, catheters are inserted through veins and positioned in the heart to record electrical activity and measure conduction intervals, which can help determine if bradycardia is due to sinus node dysfunction or atrioventricular conduction abnormalities by measuring parameters such as sinus node recovery time and HV intervals 1.
Recommendations
- In patients with symptoms suspected to be attributable to bradycardia, an electrophysiology study (EPS) may be considered in selected patients for diagnosis of, and elucidation of bradycardia mechanism, if initial noninvasive evaluation is nondiagnostic, with a Class IIb recommendation and Level of Evidence C-LD 1.
- The findings from EP studies can guide treatment decisions, particularly regarding the need for permanent pacemaker implantation in patients with intermittent or suspected bradycardia that hasn't been documented through conventional monitoring 1.
From the Research
Role of Electrophysiological Study in Symptomatic Bradycardia
The electrophysiological (EP) study plays a significant role in the investigation of symptomatic bradycardia, particularly in patients with atrioventricular (AV) conduction disturbances. Some key points to consider include:
- In sinus bradycardia, the role of EP studies is not established 2
- In AV conduction disturbances, an EP study may be necessary to establish atrioventricular block as the main cause of symptoms and to identify the anatomic site of block, which may dictate the potential need for permanent pacing 2
- A thorough history and physical examination should be conducted to determine the underlying causes of bradycardia, including sinoatrial node dysfunction or AV block 3
- Management of bradycardia is based on the severity of symptoms, underlying causes, and presence of potentially reversible causes or adverse signs 3
Diagnostic Approaches
Diagnostic approaches for bradycardia include:
- Electrocardiographic findings to recognize common bradydysrhythmias 4
- Evaluation of underlying etiologies, such as reflex-mediated, metabolic, environmental, infectious, or toxicologic causes 4
- Assessment of symptoms, as treatment should rarely be prescribed solely on the basis of a heart rate lower than an arbitrary cutoff or a pause above certain duration 5
Treatment Options
Treatment options for bradycardia include:
- Pharmacologic therapy, such as atropine or beta agonists 4
- Pacing, including transcutaneous or transvenous pacing 4
- Pacemaker implantation, which is the mainstay treatment option for sick sinus syndrome (SSS) 6
- Alternative therapies, such as gene-based bio-artificial sinoatrial node and cell-based bio-artificial pacemakers, which are promising but require further establishment of long-term safety and efficacy 6