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

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 16 August 2025Updated: 16 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

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.

Educational content only. Always verify information and use clinical judgement.