Nonspecific ECG Abnormalities in Syncope: Causal Mechanism or Incidental Finding?

Nonspecific electrocardiographic (ECG) abnormalities are common in patients presenting with syncope, but their presence does not necessarily establish the mechanism of transient loss of consciousness. The frontal QRS-T angle has recently been proposed as a marker for identifying cardiac syncope in the emergency department. However, it may reflect structural and electrical abnormalities and coexist with syncope without being mechanistically related to the event. In the reported cohort, most patients classified as having cardiac syncope had structural cardiac conditions, while only a minority were assigned an arrhythmic etiology; among the latter, atrial fibrillation with rapid ventricular response predominated, with no ventricular tachyarrhythmias reported. These findings highlight a broader limitation in the interpretation of nonspecific ECG abnormalities in syncope: association with cardiac disease or cardiovascular risk does not establish causation of the syncopal event. Distinguishing ECG findings that are incidental to the event from those that identify a plausible mechanism of transient cerebral hypoperfusion is essential for etiological diagnosis of syncope.