Clinical classification of syncope.

Area of Science:

• Cardiology
• Neurology
• Internal Medicine

Background:

• Syncope is a symptom, not a diagnosis, necessitating etiological investigation.
• Current clinical practice primarily classifies syncope based on its underlying cause to guide management.
• Reflex syncope is the most common etiology, accounting for approximately 60% of presentations.

Purpose of the Study:

• To evaluate the current etiological classification of syncope.
• To compare the etiological classification with a mechanism-based approach using implanted ECG loop recorders (ILRs).
• To determine the most effective classification system for risk stratification and clinical management of syncope.

Main Methods:

• Review of current clinical practices for syncope classification.
• Analysis of the utility and limitations of implanted ECG loop recorders (ILRs) in syncope diagnosis.
• Comparison of etiological versus mechanistic classification systems.

Main Results:

• Etiological classification is the current standard, identifying reflex syncope (60%), orthostatic hypotension (15%), arrhythmic syncope (10%), and structural heart disease (5%).
• A mechanistic classification using ILRs is limited by early-stage implantation and lack of ambulatory blood pressure monitoring.
• Vasodilation-induced hypotension, a key trigger, is not detectable with current ILR technology, hindering mechanistic classification.

Conclusions:

• The etiological classification remains the primary basis for syncope risk stratification and clinical management.
• Technological limitations of ILRs, particularly the absence of blood pressure monitoring, preclude their use as a primary classification system.
• Further advancements are needed to incorporate mechanistic insights into syncope classification and management.