Which red flag symptoms in a patient with syncope should prompt immediate referral to secondary care?

Red flag symptoms in a patient presenting with syncope that should prompt immediate referral to secondary care include:

• History or physical signs of heart failure.
• Syncope occurring during exertion.
• Family history of sudden cardiac death in people younger than 40 years and/or an inherited cardiac condition.
• New or unexplained breathlessness.
• Presence of a heart murmur.
• Any abnormality on a 12-lead ECG, including conduction abnormalities (e.g., complete right or left bundle branch block, any degree of heart block), long or short QT interval, ST segment or T wave abnormalities, inappropriate persistent bradycardia, ventricular arrhythmias, Brugada syndrome, ventricular pre-excitation, ventricular hypertrophy, abnormal T wave inversion, pathological Q waves, sustained atrial arrhythmia, or paced rhythm.
• Transient loss of consciousness (TLoC) without prodromal symptoms in people aged over 65 years.
• Syncope associated with injury or incomplete recovery of consciousness.

These features require urgent cardiovascular assessment and referral, ideally within 24 hours, to a specialist service for further evaluation and management.