Which symptom is a red flag indicating a potential cardiogenic cause of syncope?

Syncope during exertion is a significant red flag that suggests a potential cardiogenic cause of syncope. This is because exertional syncope can indicate underlying cardiovascular issues such as arrhythmias, structural heart disease, or ischemia, which may compromise blood flow and lead to loss of consciousness during physical activity.

In contrast, syncope that occurs while standing may suggest orthostatic hypotension, which may not necessarily have a cardiac origin. Similarly, syncope accompanied by nausea could be related to non-cardiac causes such as vasovagal syncope or gastrointestinal issues. Lastly, syncope occurring after eating might indicate postprandial hypotension, another non-cardiac-related issue, often seen in older patients. Thus, while all scenarios should be assessed carefully, syncope during exertion is particularly concerning for potentially serious cardiogenic problems.